The National Association for Stock Car Auto Racing (NASCAR) makes and enforces numerous rules and regulations that transcend all racing series.
NASCAR issues a different rule book for each racing series; however, rule books are published exclusively for NASCAR members and are not made available to the public. Still, many of the rules, such as the scoring system, have been widely publicized both by NASCAR and the media.
Each car is required to display its number on each door of the car and on its roof. The front of the car and bottom of the rear bumper are required to match the decal specifications of the car manufacturer. Each car is required to display a series of around 30 NASCAR sponsor decals just to the left of each door and on the front fenders. These contingency decals represent series sponsors and bonus money teams are eligible to earn during the race, but may be omitted in the event in which they conflict with the team's sponsors or moral beliefs. The series sponsor's logo is displayed on top of the windshield, called the windshield header or windshield banner.
Beginning in 2013, the livery layout for the NASCAR Cup Series was altered, coinciding with the change to the Generation 6 model car. In lieu of the series sponsor like in lower series, the windshield prominently features the last name of the driver (as well as first name or first initial in the case of siblings and family members, as is the case for both Busch brothers, or suffixes for drivers such as Dale Earnhardt, Jr. and Martin Truex, Jr.) placed in the center of the windshield header. Logos of the manufacturer are placed on each corner of the upper windshield. Number and sponsor logos were barred from being placed on the headlights and taillights, as not to obstruct each car model's unique characteristics. A new location for a single sponsor logo, however, was added to the rear of the roof adjacent to the number. In 2014, a new layout was created for participants in the NASCAR Chase for the Championship, requiring the cars to feature yellow roof numbers, front splitters and front fascias. The background of the windshield header would also be colored yellow, with the driver's name displayed in black lettering. A new Chase for the Championship logo would replace the normal NASCAR Cup Series logo in the contingency group. A decal would also be placed next to the driver's name above the door to signify each win a driver earned that season. For 2015, the liveries of the Xfinity and Camping World Truck Series would feature the driver's last name on the upper rear window. Starting in 2017, the Monster Energy logo is now on the front windshield with the driver name moving to the rear windshield in the Monster Energy NASCAR Cup Series.
Outside of these requirements, teams may design the car and place sponsor logos in NASCAR-approved locations, and must submit all paint and graphics schemes and all sponsor identity to NASCAR in advance for approval. One paint scheme requirement for example is that both the driver and passenger side of the car must share the same color pattern, though the front and rear may be different colors. This safety rule, to avoid confusion for spotters, NASCAR officials, and other drivers, was brought into light in October 2014 at Talladega, when Terry Labonte's Go FAS Racing team painted his No. 32 car in two different color schemes as a tribute to the two-time champion, but prior to NASCAR approval. NASCAR allowed the team to retain the scheme for knock-out qualifying, but forced them to match the two sides for the race. However, by 2016, it seems that NASCAR has either quietly removed this rule or allowed teams to race with a split-side scheme as long as they got the permission to do so, as seen with John Hunter Nemechek's No. 8 truck in the 2016 American Ethanol E15 225 and both the No. 3 and No. 31 cars of RDV Compétition during the 2016 NASCAR Whelen Euro Series.
Teams apply to NASCAR for the use of a car number, and pay for the rights to the number's likeness. NASCAR legally owns and controls all rights to car numbers. When drivers change teams, the team owner usually retains the number. Unlike in other series, such as the former IROC Series, there is no provision for the defending series champion or the points leader to adopt car number 1; it is available to any team. Only one number, No. 61, in the Whelen Modified Tour, has been retired, in memory of nine-time series champion Richie Evans, who was killed at Martinsville Speedway practicing for the final race of the 1985 season. Other historically significant numbers have been ceremoniously retired, except with the permission of the driver or team owner. The number 3 for example, used by Dale Earnhardt and his car owner Richard Childress, has been unofficially retired for all teams and drivers except for an Earnhardt or Childress family member, with Childress paying a licensing fee while the number was out of circulation from 2001 to 2013. In other instances, a number has been relinquished due to a sponsor leaving a team. After the 2002 season, Robert Yates Racing switched from their longtime number 28 to 38 after sponsor Texaco-Havoline ceased their sponsorship.
Teams can run numbers from 0 to 99 (as well as 00 to 09), but no two cars can display the same number during a race. Teams that run 00 to 09 are listed as 100 to 109 for NASCAR's scoring purposes. Except for those numbers (which have been used for full-time teams), part-time teams may be assigned a three-digit number for scoring purposes only (such as Nos. 141 and 241). If two such teams arrive with the same two digit number, the team higher in championship points prevails, and the other team will be forced to change their number for the race.
Although NASCAR has a long history of tobacco sponsorship, following the 2003 season, longtime NASCAR partner R. J. Reynolds declined to renew their Winston sponsorship of the Cup Series, replaced by Nextel Corporation. In June 2010, the Food and Drug Administration passed new regulations preventing sponsorship for cigarettes or smokeless tobacco products in any sporting event, including auto racing events. The announcement affected two teams: the No. 33 Truck of Ron Hornaday, Jr. and Kevin Harvick, Inc. lost its Longhorn Moist Snuff sponsorship, while the No. 27 Nationwide Series car of Baker Curb Racing lost its Red Man sponsorship. Baker Curb would shut its doors the next year due to lack of sponsorship.
In spite of the legislation, tobacco sponsorship continues in the sports through electronic cigarettes, with companies such as Green Smoke, blu (owned by R.J. Reynolds), and Arrowhead sponsoring NASCAR teams. A brand of herbal smokeless tobacco, Smokey Mountain, has also sponsored drivers such as Hornaday, Johnny Sauter, Brian Scott, and Daniel Hemric.
Though NASCAR typically promotes competition between multiple brands, including those that sponsor the sport and individual races, the sanctioning body provides exclusive protection to its series title sponsors, such as Monster Energy in the Cup Series, as well as current fuel supplier Sunoco. This policy, known as the Viceroy rule, prevents sponsorship from direct competitors within a certain series, although it does not prevent a company from moving to a different series within the sport, or advertising a product that does not directly conflict with the title sponsor. For example, Royal Dutch Shell, Texaco and other oil companies have been allowed to promote their motor oil brands (Pennzoil and Havoline respectively) but not their gasoline products. When a new title sponsor creates conflicts with existing team sponsors, NASCAR typically allows the team sponsors to remain under a grandfather clause. The rule is named after the British cigarette brand Viceroy, and is in reference to the 1972 USAC Championship Car season during which title sponsor Marlboro renounced its branding when Viceroy entered the sport to sponsor entries.
The rule has come into effect on several occasions, most notably when Nextel Communications signed a ten-year $700 million deal to replace Winston as the Cup Series sponsor. Active sponsors Cingular Wireless (sponsoring Richard Childress Racing's No. 31 team) and Alltel (sponsoring Team Penske's No. 12 car of Ryan Newman) were allowed to continue their deals, but both sponsor agreements were put into question when the companies were purchased and sought re-branding. In 2004, Robby Gordon was required to wear a full color Nextel patch on his driving suit. He had worn a dark gray on black subdued Nextel patch when he was sponsored by Cingular when racing for RCR. Between 2007 and 2008, NASCAR and AT&T Mobility (the successor to Cingular) filed suits against each other, with NASCAR seeking to kick all telecommunications companies out of the top series. AT&T was allowed to remain in the sport until 2008. Meanwhile, Verizon, after purchasing Alltel in 2008, moved its sponsorship to the Penske entries in the Xfinity Series and later the IndyCar Series, while the team ran a similar scheme in the Cup Series without Verizon branding until 2010. In a separate 2007 incident, Robby Gordon was allowed to retain his sponsorship from mobile phone manufacturer Motorola after adding logos referring to the company's "Digital Audio Players".
A combination race is a race run between multiple series that operate under compatible rules packages. During NASCAR's combination races (currently the two K&N Pro Series (East and West), and formerly the Winston Cup Series/Winston West Series and Busch Series/Busch North Series), there is one race, but points are scored for both series. In previous years, drivers were given points based on how they finished among competitors from the same series. For 2017, drivers will receive points in their series based on their actual finish in the race among all competitors. However, drivers who declare they are running for a championship in both series (East & West) will be awarded points in both series, provided they have the appropriate license for both.
Special rules apply as two teams will have the same number. The fastest lap time in qualifying determines which team will have the number for the race, and which team must temporarily change the number for the race. For example, during the 1991 Busch Series season, there were selected races in the Northeast (Loudon, Nazareth, Dover, Oxford) where both the Busch Grand National (now Xfinity) and Busch Grand National North (now K&N Pro East) Series raced in combination races. North team Ricky Craven (also drove his car) and Grand National team Don Beverly Racing (Jimmy Hensley driving) both used No. 25. Whoever had the faster qualifying time in each race used No. 25. Craven used No. 28 at Oxford when Hensley had the faster time, while Hensley used No. 5 when Craven had the faster time at Loudon. Both teams, however, scored respective owner points for the No. 25 in their respective series.
Teams must use a single car from the start of the first practice session through the end of the race. Teams that crash a car in practice or qualifying may go to a backup car, but racing a different car from the one that passes the initial inspection results in that car having to start at the rear of the field.
Engine and transmission changes are prohibited during a race weekend. Xfinity and Truck Series engines must last two race weekends, excluding restrictor plate races. Cup Series teams are restricted in the number of engines they may use in a season (13 engines at minimum must last at least two race weekends), effectively a limit of 23 engines during the season. Changing either will result in starting in the rear of the field. Transmission changes are allowed during road course weekends and during the race weekends at Pocono Raceway.
Driver changes are permitted, however starting the race with a different driver than whom qualified the car will result in the car starting at the rear of the field. Driver changes during the race are permitted as well, performed during pit stops, but a team must incur any loss in position due to time spent swapping drivers. The driver who starts the race earns all the points, statistics, and purse money.
When the yellow flag is displayed and the yellow caution lights around the track come on, the field is frozen immediately at the moment of caution. All scoring ends immediately and cars are to slow to pace vehicle (safety car) speed. Cars will line up behind the pace vehicle in the order in which they passed the last scoring loop on track (there are as many as 18 loops around the track, although the one at the start/finish line is the only one that counts for official race statistics). The exception to this rule is if the yellow flag waves after the white flag is thrown (or, in the case of an overtime attempt, if the yellow flag waves after the race leader has crossed the overtime line) or if the race will not be restarted (typically for rain; but sometimes for darkness if a track does not have night lights), in which case NASCAR will use video evidence to determine the finishing order.
When the caution comes out, the pit lane is immediately closed, a rule first implemented following the 1989 Atlanta 500. This is shown by a flashing red light at the entrance to pit road. Entering pit road when it is closed (with certain exceptions) is a penalty of restarting at the rear of the field. When pit road is open, a steady green light will appear at the entrance to pit road, and a green light will come on in the rear window of the pace vehicle.
During a "quickie yellow" all cars may enter pit road the first time by when it is opened. After the pit stops, the first car one lap down at the moment of caution (known as the free pass car) is permitted to go around the pace car and start the race at the rear of the field, but back on the lead lap.
During a full yellow, only lead lap cars may pit the first time by the pit road. Once the lead lap cars who have decided to pit have entered pit road, the free pass car will be sent around the pace car to earn their lap back. The next time by, all cars (including the free pass car) may pit.
Cars may pit as often as they wish at the expense of track position, but the free pass car is limited to taking fuel only at the first pit stop opportunity. If the free pass car is judged to have caused the caution (intentionally or not) there will be no free pass car.
At the one to go signal, the pace car will turn its lights off. At this point, any car that is ahead of the leader of the race will be waved around to the rear of the field. These cars are not permitted to pit until after the green flag comes back out and the race has resumed. The field will then line up double file for the restart. The leader of the race gets lane choice, but the third place car (and odd positions on back) will always start in the inside line, while the fourth place car (and even positions on back) will always start in the outside lane. The restart order is always this: Lead Lap Cars > Cars 1 or more laps down > Free Pass Car > Wave Arounds > Cars who have received a penalty.
Once the pace car has pulled into the pits, there is a restart "zone" consisting of lines painted on the outside wall of the track. The leader of the race is to begin accelerating inside this zone to resume the race. If they do not, the flagman controls the restart. The second place car may not be ahead of the leader at the moment of green flag, however either car on the front row may cross the start/finish line first. Passing is not permitted until the leader of the race crosses the start-finish line. Lane changes are also not permitted until after a car clears the finish line.
Per the NASCAR rule book, a restart is official once the legal lead car crosses the start/finish line. If the green flag is waved, but NASCAR calls off the restart because of an incident before the leader crosses the start/finish line, the restart is deemed aborted.
Like most other sanctioning bodies, NASCAR will use flags to provide the drivers with information regarding track conditions. NASCAR, not adhering to the FIA rules (despite NASCAR being a member club of ACCUS, the U.S. motor racing sporting authority and representative to the FIA World Motor Sport Council), does not use the flag system outlined in the FIA International Sporting Code. Major differences include that in NASCAR (and other championships in North America) the white flag is used to signal that the leader is on the last lap, in FIA ISC regulated events (such as Formula One and most European championships) it is used to signal that a slower car is on track. Also, the blue flag specified in the FIA ISC does not have a diagonal stripe, and the black flag means that a driver is disqualified.
|The green flag indicates that the race has started or restarted. It is shown by the official in the flag stand when the leader enters the designated restart zone, which is located a short distance before the start/finish line.|
|The green and white checkered flag is shown to indicate the end of a race stage. After the top 10 drivers cross the start/finish line, the caution flag is displayed.|
|The yellow flag, or caution flag, indicates a hazard on the track -- most often an accident, but sometimes also for debris, light rain, emergency vehicles entering (usually on short tracks with no tunnel) or a scheduled competition caution (usually used for races that have been postponed due to inclement weather). All cars must slow down and follow the pace car. Passing is not allowed under the yellow flag. NASCAR experimented the "local yellow" flag in road courses; cautions apply to the entire circuit, including road courses.|
|The red flag indicates that the race has been stopped. This may happen due to a large accident (such as a multi-car wreck like The Big One), inclement weather, track repair (such as damaged catch fencing), or for severe track cleaning (such as the final laps, when NASCAR may clean the entire track to ensure the race can finish under green flag conditions, and to do so with the track clean of oil from engine failure or crashes). Cars may be ordered into the pits or on the track depending on conditions; red flags for inclement weather generally result in all cars parking in the pits. Race teams are not permitted to repair or adjust cars during red flag conditions. However, drivers may exit their cars, and they may be provided with water, food or other necessities. In some races, like the All-Star Race, a red flag is used to indicate a predetermined pause in the race. This flag is also used with the black flag to signal the end of a practice or qualifying session.|
|The white flag indicates one lap remaining in the race. More specifically, it indicates that all drivers will be scored for at most 1 more lap after passing the white flag.|
|The checkered flag indicates that the race is over.|
|The black flag indicates that a driver must pit immediately. This flag is shown if the driver or pit crew violates a rule (e.g., speeding through the pits), if the vehicle has sufficient mechanical damage that it is a hazard to other drivers, if the vehicle cannot maintain the minimum required speed (varies by track; typically disclosed in the pre-race drivers' meeting), or if a driver has been driving overly aggressively. In the event of a failure of the in-car radio, NASCAR will, at the team's request, display the black flag to signal a driver to pit, one time only.|
|The black flag with a white cross indicates that a driver is no longer being scored. This is normally shown if a driver does not respond to a black flag within three laps.|
|The blue flag with a yellow stripe is shown to warn slow drivers of faster cars approaching. NASCAR rarely black-flags drivers for not obeying this flag; however, it is frequently displayed and warnings may be given if it is blatant (such as a lapped driver blocking for a teammate). NASCAR uses the yellow diagonal stripe on the blue flag because the flag is usually displayed on top of the starter's stand, and not at eye-level to the driver from the track.|
|The blue flag is used to indicate an area on a road course where drivers should be careful due to slow or stopped cars or a partially blocked track. It is not used on ovals. If a full-course caution is required, NASCAR will use the yellow flag to indicate this. Unlike the local caution commonly used in other racing series, the blue flag is not a "local caution" and does not prohibit overtaking; rather, it merely tells drivers to be careful. Safety workers will not leave their designated spots and enter the track under this flag. In the wake of a fatal corner worker crash at Daytona International Speedway in 2004 in a non-NASCAR sanctioned race (but using track workers), NASCAR has become reluctant in recent years to use local cautions, opting to use the full-course yellow caution flag instead if any safety team members have to approach the track in an attempt to give safety workers a safer environment to inspect debris by forcing all cars under pace car speed, instead of race speed, to remove debris. The rationale is most of the field will be packed together while cleanup is happening, instead of being spread over the entire track.|
A knockout system similar to Formula One is used. During the time allotted, teams are allowed unlimited attempts to qualify with their fastest lap of each round counting as their official time.
Between attempts, cars are parked on pit road, where teams may hook up a cooling system through the cowl flap in front of the windshield to cool the engine. However, teams are not permitted to raise the hood or make other significant adjustments during qualifying. Also, tires may not be changed without approval from NASCAR, who will only grant approval in cases of flat tires or safety issues.
On all open engine ovals in the Monster Energy NASCAR Cup Series, tracks shorter than 2 miles in the Xfinity Series, and tracks shorter than 1.5 miles in the Camping World Truck Series, round 1 is 15 minutes long. The fastest 24 advance to round 2 which is 10 minutes long. The fastest 12 advance to round 3 which determines pole position. In addition to determine who advances to round 2, round 1 also determines who will and will not qualify for the race and starting positions 25-40 (Cup Series), 25-40 (Xfinity), or 25-32 (Camping World Truck). Similarly, round 2 will determine starting positions 13-24, with round 3 determining positions 1-12.
On road courses, there are only two sessions: Round 1 is 25 minutes with the top 12 advancing to Round 2 which is 10 minutes.
In the event rain falls between rounds, NASCAR has the option of declaring the session over and the speeds from the previous round will count for all remaining starting positions.
Due to how the draft works in restrictor plate racing, and a series of crashes in qualifying during 2015 Speedweeks, a single car qualifying format is used for restrictor plate racetracks. In July 2015, after making rules changes to the cars designed to increase drag and drafting, NASCAR used the format at Indianapolis and Michigan (but discontinued its use at both tracks for 2016). The single car system will only be used at the plate tracks, ovals 2 miles and longer in the Xfinity series, and ovals 1.5 miles or longer in the Truck series.
In round 1, cars are sent out one at a time at the direction of a NASCAR official. Each car has one warm-up lap, one timed lap, and one cool down lap. NASCAR will release cars roughly half a lap apart to prevent any aerodynamic advantage from being gained from a competitor's car. The order in which cars go on track is the inverse of practice speeds. As with the road course format, the top 12 cars advance to the final round.
After the final car has returned to pit road in the first round, all 12 qualifying teams may hook up the cooling system to the car for 10 minutes. Round 2 cars qualify from slowest to fastest according to their speeds from round 1. The fastest car will win the pole.
The session results from single car qualifying set the starting lineups for the Can-Am Duel races on Thursday. The duel races are two 60 lap/150 mile races. The first race consists of those who finished qualifying in odd-numbered positions and sets the lineup for odd-numbered positions in the 500. The second race does the same for even-numbered positions. However, there must be an equal number of "open" or "non-chartered" teams in each Duel race. After the Duel races, the lineup is set as follows:
All three NASCAR national series will set a specific number of starting positions by timed laps and have a specific number of starting positions based on owner points of vehicles that have not already qualified.
In the Monster Energy NASCAR Cup Series four positions are awarded to the fastest qualifying open teams. In the Xfinity Series, six positions are awarded based on owner points to cars not already qualified. In the Camping World Truck Series, four positions are awarded based on owner points to trucks not already qualified.
The final position in the Xfinity Series and Camping World Truck Series is reserved for a past series champion. Each past champion can use this past champions' provisional up to six times per season. If the past champions' provisional is not needed, then the position goes to the first team in owner points not already qualified for the race. If a former champion driver's team is one of the top six or four teams, respectively, highest in owner points, not already qualified, then that does not count against usage of the provisional. If there are 40 or less (or 32 or less) vehicles entered in the respective races, no provisionals are charged and the field will be determined by timed laps only.
After these positions are awarded, the cars are arranged by lap times.
In 1991, NASCAR introduced the past champion's provisional (sometimes known as the "Petty rule") after Richard Petty failed to qualify in four races in 1989, which resulted in a viewership ratings drop that season. This special provisional allowed a former Cup champion to claim the final starting position if he was too low in the points standings and was unable to qualify by speed. The past champion's provisional worked perfectly until 1997, when Darrell Waltrip failed to make the UAW-GM Quality 500 lineup because Terry Labonte was the more recent champion and was higher in points. NASCAR considered revising the guidelines to the past champion's provisional after Waltrip used it to enter 20 races in 1998.
In 2004, NASCAR gave past Cup champions a maximum of 10 past champion's provisionals per season; this number was reduced to six in 2007. This proved disastrous for Dale Jarrett in 2007, as he moved to a fledgling Michael Waltrip Racing with no owner points and failed to qualify in 12 races after being forced to use all of his past champion's provisionals at the start of the season. In 2013, NASCAR once again revised the past champion's provisional rule, allowing past champions only one every six races; this meant that the drivers needed to qualify in the succeeding six races to earn their next provisional.
The past champion's provisional was discontinued from the Monster Energy NASCAR Cup Series as part of the new Charter system and qualifying system in 2016.
The Open uses the standard procedure, but with only 8 cars advancing to the final round. All-Star race qualifying consists of the combined time of 3 laps with a 4-tire pit stop. The fastest 5 drivers in the opening round advance to the final round.
The Eldora Dirt Derby has a unique qualifying format. Each truck will take two timed laps, with the faster lap counting as that truck's official time. The trucks are assigned to one of five heat races where the top five trucks from each will advance to the feature. Those that fail to qualify will have one last chance race, where the top two trucks will also advance. Provisionals will be determined after the last chance race.
The Advance Auto Parts Clash is an annual invitation-only race held the weekend before the Daytona 500, and sets its lineup via a random draw.
The following is a list of NASCAR penalties. Penalties listed as "NASCAR Discretion" can result in a simple restart at the tail of the field, a multiple lap penalty, or disqualification.
NASCAR conducts a complete technical inspection prior to the first practice session, before and after qualifying, and before the race. A quick safety inspection is also completed prior to each practice session after the first. Penalties for car violations are typically announced the Wednesday after a race, and can range from a simple fine to a suspension (typically a maximum of 12 races) and loss of points. After a race, the top 5 finishers, one other random car, and the first car failing to finish the race not due to an accident will have their cars inspected. The winner, random car, and first car out also have their cars and engines taken by NASCAR for further inspection at the NASCAR Research and Development Center. Further, there is one random race per year where NASCAR confiscates 15-20 engines and takes them to NASCAR's Research and Development Center for evaluation, comparison, and to help decide on future rule changes.
Starting in 2017, NASCAR will attempt to issue more penalties during a race weekend instead of waiting until Wednesday. There will now be L1 and L2 penalties:
As a member of ACCUS/FIA, NASCAR has a substance abuse policy requiring random testing of drivers, crew members, and officials. Those who have violated the policy (including suspensions for domestic violence) are suspended indefinitely immediately and given the opportunity to enroll in NASCAR's Road to Recovery program to be re-instated into NASCAR.
On January 28, 2019, NASCAR unveiled its new Sports Betting Policy, which prohibits team owners, drivers, crew members and series officials from gambling on NASCAR or disclosing confidential information that could enable or facilitate betting on NASCAR events. Offenders could face fines of up to $200,000 as well as indefinite suspension or termination. NASCAR will continue to permit members to take part in fantasy sports provided the prize value is under $250. The new policy was in reaction to the May 2018 Supreme Court of the United States ruling that struck down the Professional and Amateur Sports Protection Act of 1992, which allowed US states to authorize legal wagering.
During a race, teams must pit several times for refueling and new tires. Teams are permitted five crew members over the wall at the start of the race; that consists of two tire changers, one tire carrier, a jackman, and a gas man. Once NASCAR gives the OK (usually once the leader begins lapping cars), a 6th crew member is permitted only to service the driver/windshield. With the 2018 NASCAR rule changes, the gas man is now not allowed to make any adjustments to the car when refueling it.
There is an established pit road speed limit for each race. Since NASCAR cars do not have speedometers, the first pace lap of each race is run at pit road speed so drivers can get a tachometer reading for pit speed. There are a variety of other safety rules (see penalties above) that must be followed.
At the moment of caution or when there are two laps to go in the stage, pit road is immediately closed. NASCAR uses both a light at the end of pit road and a series of cameras to help determine the moment pit road is closed. The pits are opened once the field is under control of the pace/safety car unless there is an accident near the entrance/exit or on pit road, in which case the pits will remain closed until NASCAR deems the pits are safe to open.
After an incident at the June 2015 Chicagoland Xfinity race where the pit flagman waved a green flag but the light at the end of pit road was red, NASCAR added a light to the rear of the pace/safety car to help inform drivers and teams when pit road will be open, and thus removed the flagman from the entrance of pit road. NASCAR's official policy is that in the event of a discrepancy, the light at the end of pit road is official.
Starting in 2017, cars sustaining accident damage that cannot be repaired on pit road within 5 minutes will automatically be removed from the rest of the race. Speeding on pit road will see that time reduced by 15 seconds per infraction. Further, teams are not allowed to replace bodywork once the race begins. Teams using more than 5 crew members will also have their car removed from the race.
For the 2018 season, NASCAR created a new roster system. This system would standardize the number of at-track team members. Rosters are split into three categories: Organizational, Road Crew, and Pit Crew.
Examples of Organizational roster spots include competition director, team managers, technical director, IT specialists. In the Monster Energy NASCAR Cup Series, teams are allotted three organizational roster spots for one- and two-car operations, and four spots for three- and four-car outfits. XFINITY and Gander Outdoors Truck Series teams are allowed one organizational roster spot each.
Examples of Road Crew include crew chief, car chief, mechanics, engine tuners, engineers, specialists (for areas such as tires, aerodynamics and shocks) and spotters. The limits for these personnel by series: Monster Energy Series, 12; XFINITY, 7; Gander Outdoors Trucks, 6.
Pit Crews are the same in all series, with the maximum number being 5.
The exceptions to these numbers are slight. Monster Energy Series teams are allowed one extra road crew position at Indianapolis Motor Speedway and the three road courses (Sonoma, Watkins Glen, Charlotte), where teams often use multiple spotters. Also, an additional road crew roster spot will be allowed for XFINITY teams at 10 races and Truck Series teams at five. 
Starting in 2017, NASCAR announced they may reserve the right to move up the start of the race one hour to beat inclement weather (heavy rain and lightning on road courses).
Two hours before the race, drivers and crew chiefs attend a mandatory driver's meeting. They are required to attend in person, and no exceptions are allowed (which has caused trouble with drivers attempting the Memorial Day Double). Failure to attend the meeting will force drivers to start at the rear of the field. In August 2015, NASCAR announced they would experiment moving the driver's meeting to only one hour before the race since meetings at most races take less than 15 minutes.
Roughly a 30 to 45 minutes before the race start time, driver introductions will be held. Failure to attend these will also require the driver to start at the rear of the field as well.
At the designated start time, a pre-race invocation is given, followed by the singing of the national anthem. Once the anthem is complete, drivers have exactly five minutes to get in their cars with all the safety equipment fastened and ready to go. At the end of those five minutes, the grand marshal for the race will deliver the command "Drivers, start your engines!", at which point each car must start its engine. With the engines running, the cars sit on pit road for approximately three minutes before heading on the track for some warm-up laps before the pace car. The average number of pace laps is three, but there can be more or less depending on a wide variety of circumstances and conditions, including but not limited to track length, track drying efforts after rain, or if a car has a problem and stops on the track during those pace laps. At the end of the pace laps, the field will partake in a rolling start.
If the last lap of the race is started under caution, the race will be extended per NASCAR Overtime. Once the track is clear, the field will be given the green flag with two laps remaining. If there is another crash/caution before the leader reaches the start/finish line, then the race will continue to be extended until the leader reaches the line. However, when the leader of the race reaches the start/finish line, the next flag (caution or checkered) will end the race (although competitors are required to cross the start/finish line at pace car speed to be scored in their position at the moment of caution).
After the race, the winning driver (and, if at the end of the season, championship winning driver) will usually complete a series of burnouts in celebration of their victory, before heading to victory lane for more celebrations and post-race interviews.
Since late 2001, a head and neck restraint has been required for usage of all drivers. Since 2005 the HANS Device (Head and Neck Support Device) has been the only such approved device. Since 2003, helmets have been required for pit crew members as well. Drivers and pit crew members must also wear firesuits. Drivers are required to use carbon fiber seats and headrests for strength and durability. Cars have also been redesigned since the 2001 death of Dale Earnhardt and after spectacular crashes to reflect new discoveries and developments in safety.
All oval tracks in any of NASCAR's National Series (except Eldora) use the SAFER Barrier and other soft wall technology to lessen impacts.
After a series of flips and dangerous crashes in the 1980s, NASCAR began requiring all cars to run a restrictor plate at Daytona and Talladega. The restrictor plate limits air into the engine, reducing horsepower and speed at these tracks from 230-240 mph to 195-200 mph. At these races, in addition to the restrictor plate, there are a variety of other technical rules and regulations to keep the cars stable and on the track. In addition to these technical rules, restrictor plate races are the only races where drivers are prohibited from using the apron of the track to execute a pass. A double yellow line separates the track from the racing surface, leading many to call the rule the "Yellow Line Rule." Driving under the line to advance one's position is subject to a drive-through penalty, or if the foul occurs on the last lap that car will be relegated to the last car on the lead lap in official race results.
NASCAR previously sanctioned an annual 4-day pre-season test at Daytona International Speedway in January for all teams until 2015, when all private testing was banned. After that test, each organization was allowed four 2-day tests. Each test was required to be at a different race track. Rookie drivers were allocated an additional test. Beginning in 2016, each team is eligible to participate in five open tests that will occur at Indianapolis Motor Speedway, Watkins Glen International, Chicagoland Speedway, and Homestead-Miami Speedway.
Tire supplier Goodyear is allowed unlimited testing and can ask whichever teams it wants to complete the test. Usually Goodyear chooses the top three finishers from the previous year's event to run the test. However, Goodyear formerly staged a full-field tire test at Indianapolis in late June/early July in preparations for the Brickyard 400.
The Monster Energy NASCAR Cup Series usually runs one day of practice and qualifying on Friday, followed by a second day of practice on Saturday morning, followed by the race on Sunday. If running a Saturday night race, the second day of practice is not held. During impound races, the three-day schedule is maintained, with qualifying taking place of Saturday practice.
The Xfinity Series will run practice on Friday, followed by qualifying a few hours before the race on Saturday. If a race is on Friday (or the schedule is otherwise compacted for other reasons), it is not uncommon for practice, qualifying, and the race to all be held on the same day. The Camping World Truck Series usually does this.
Rain can and often does affect the weekend schedule. When it does, qualifying is routinely cancelled and the starting lineup is set by owners points (previous year's points for the first 3 races). Whenever a race is postponed due to rain, then the race is usually scheduled for the following day (i.e., a Saturday night race postponed to Sunday afternoon or a Sunday afternoon race postponed to Monday afternoon).