NASCAR 101: A Terminology Guide to NASCAR Racing

Like any sport, NASCAR is very unique and has a very unique terminology that is only shared between a few other sports. In order to understand the sport, I’ve put this list of common terms together for fans who are new to the sport and fans who need a quick refresher.

Some of these terms will require knowledge of other terms listed in the article, so be sure to read the whole list. These terms will be used by many people who discuss racing, including myself when I write these articles. 


Photo credit: Getty Images Graphic overlay by Joe Passero

Air ducts – A pair of tunnel-like structures in the nose of the car which allow air to pass through the nose and out from the front wheel wells, widening the wake in the air which the car produces. These are only used on tracks which utilize the high downforce/low horsepower package, which are tracks between 1.33 and 2 miles in length.

A-post – The bodywork which attaches the roof to the sides of the car between the front windshield and the front windows on the sides of the car.

Brake ducts – Holes in the nose of the car which are attached to hoses that run to the brakes. The air that travels through the hoses helps keep the brakes cool. Brake ducts are primarily run at short tracks and road courses, since those styles of racing require the most braking.

B-post – The bodywork which attaches the roof to the sides of the car between the front and back windows on the sides of the car.

Chassis – A chassis consists of the framework of the car which must sustain the various loads and forces that act on the vehicle during the race. 

C-post – The bodywork which attaches the roof to the sides of the car between the rear windshield and the rear windows on the sides of the car. 

Decklid – This term refers to the top of the trunk where the spoiler sits.

Fenders – The areas which surround the car’s tires.

Grille – Mesh wiring on the nose of the car that allows air to pass through the nose into the radiator.

Quarter Panel – The areas of bodywork on the sides of the cars behind the rear wheels.

Roll cage – Interior framework which helps protect the car’s driver in the event of a wreck.

Roof flaps – Two pieces of the roof which lift vertically from the roof of the car to create downforce on a vehicle if it begins to spin out of control. The additional downforce created by the roof flaps helps keep the car on the ground as lift increases.

Roof hatch – A piece of the roof of the car which can open to allow a driver to escape their vehicle in the event of a serious accident.

Shark fin – a clear rail which runs between the end of the roof and the spoiler of the car.

Splitter – a piece of bodywork which is attached to the bottom of the car’s nose. The splitter helps seal the car to the ground and split the air, pushing it up or below the vehicle.

Spoiler – A piece of metal on the decklid which sticks up from the car. The spoiler adds surface area to the rear of the vehicle, helping create rear-end downforce but also adding drag. The bigger the spoiler is, the more downforce and drag gets created. Smaller spoilers with less surface area don’t add as much drag or downforce to the car.

Tapered spacer – A component which limits the amount of airflow into the engine. The limitation of air going into the engine also limits the amount of horsepower and torque which the engine produces.

Window net – Because NASCAR cars and trucks do not have doors, drivers enter their cars through the driver-side window. To ensure they don’t fall out of their car in the event of a serious accident (don’t think it hasn’t happened), NASCAR requires the driver-side window to have a net called a window net.


Aero-loose/Aero-tight – Aero-tight/loose are two terms which refer to the handling of the car when temporarily affected by changes in aerodynamic forces and air pressure on the car. When the car gets aero-loose, it means that the change in air pressure makes the rear of the car lose grip. If a car goes aero-tight due to the change in air pressure, it means that the front of the car loses grip.

Draft(ing) – Drafting is a technique when one car lines up behind another to reduce the overall drag on the two cars and help the cars go faster. As a car drives on track, it punches a “hole” in the air, creating a low-pressure wake of air behind the vehicle. The low-pressure air behind the lead car allows a second car behind the first to pick up speed due to the reduced air resistance on the front of the second car. The act of drafting helps both the lead car and the trailing cars pick up speed. Cars must be traveling at a certain speed to punch a big enough hole in the air in order for drafting to be effective, so it isn’t a tactic used at some of the smaller, slower racetracks. Also because of the draft, the trailing cars can travel at the same speed as the lead car while using less throttle, which can help the trailing cars save gas.

Bump draft – In a bump draft, the trailing car’s front bumper makes contact with and pushes against the rear bumper of the lead car. The trailing car physically pushes the lead car, helping the two cars travel at the fastest speed possible.

Side draft – In a side draft, the trailing car begins the act of passing on the leading car. When the nose of the trailing car gets beside the rear quarter panel of the leading car, the trailing car will move very close to the lead car without touching. This forces the air up and over the quarter panel of the lead car and onto the spoiler, which drastically increases drag for the lead car, slowing them down and allowing the trailing car to pass the lead car. The trailing car does not pick up speed, although visually it looks as if they do.

Drag – Drag is the aerodynamic force that pushes against a car in motion. Basically, it’s a fancy word for air resistance.

Downforce – An aerodynamic force which pushes the car down towards the ground. More downforce helps cars have better grip, which can help drivers run faster in the corners.

Lift – Lift is the opposing force of downforce, as it pushes up on the car. Although lift is not a term commonly used, it’s still an important concept to know, as excessive lift can cause cars to go airborne.


Black flag – When a black flag is displayed, it is a signal to  a driver on the track that they must serve a penalty. A black flag is typically only directed to one driver, and NASCAR competition directors communicate with the penalized team as to why they must serve the penalty. If the penalty has not been served in a certain number of laps after the black flag was first displayed, the team will stop being scored until the penalty is served. 

Black/white checkered – The black-and-white checkered flag indicates the end of the race’s final lap and that the race is over.

Blue flag with diagonal yellow stripe – This flag is shown to a slow car to let them know that there are faster cars approaching from behind and will attempt to pass. This flag is only shown under green-flag conditions and is only shown to cars at a noticeable speed deficit. For example, if one car is passing another for a position in the running order of the race, they’re likely running similar speeds, so the blue flag with a diagonal yellow stripe will not be displayed. However, if the 1st-place car is getting ready to lap the 30th-place car, the flag will be displayed to the 30th-place driver to alert them that the leader is approaching fast.

Green flag – The green flag starts and restarts the race. Much like a green light on a traffic light, this flag means “go” and drivers can race under green-flag conditions.

Green/white checkered – The green-and-white checkered flag indicates that a stage has ended, but not the race. This flag is always followed by a yellow flag, per NASCAR rules.

Red flag – A red flag means the same thing in racing as it does on a traffic light: STOP! Red flags are usually displayed when big wrecks occur that take more time and more attention to clean up. The red flag will also be displayed if rain begins to fall over the racetrack. Under the red flag, the field is frozen and all competition stops, meaning that pit stops can not be performed and damage can not be repaired.

White flag – The white flag is used to indicate the start of the race’s final lap. After the race leader crosses the start/finish line to take the white flag, the next flag displayed ends the race, whether it’s a yellow or a black/white checkered flag.

Yellow flag – Also known as the caution flag, this flag slows the race down, much like a yellow light on a traffic light signals drivers to slow down. The yellow flag is usually displayed during minor wrecks. Under yellow-flag conditions, more commonly called “under caution,” cars can not advance their position.


Access road – A paved lane off the racing surface, usually connected to the apron, which allows drivers to get out of the way of traffic in the event they have an issue.

Apron/runoff – Track aprons and runoff areas are paved areas that are not part of the racing surface. On oval tracks, aprons and runoffs are always to the left of the racing surface, just off the inside line. Road courses utilize runoff areas typically surrounding the outside of corners. While aprons and runoff areas are not considered part of the racing surface, drivers can pass while driving in these areas, excluding Daytona International Speedway and Talladega Superspeedway.

Clean air – This term refers to air being driven through that is unaffected by other cars. Typically, the race leader is the only driver or one of only a few in clean air. Clean air helps the car drive a little better and leaves more in the driver’s control.

Dirty air – This term refers to air being driven through which is affected by the wakes which other cars produce when driving through it. Driving through dirty air will upset the handling of a car and produce aero-loose and aero-tight sensations.

HANS device – The Head and Neck Support (HANS) device is a safety accessory which drivers wear around their neck and shoulders. In the event of an impact, these devices restrict the driver’s head from snapping forward or backward in a dangerous and harmful manner.

Inside – The “inside” line of an oval track refers to the shortest way around the racetrack on the racing surface.

Loose – When a driver reports that their car is loose, it means that the rear of the car has less grip, which causes the rear end to swing around and possibly out of control.

Outside – The “outside” of the racetrack on an oval course is the longest way around the track, right up against the retaining wall.

Pit road – Pit road is a part of the track off the racing surface where drivers can bring their cars to be serviced. Each car in the race has a small area called a pit box or a pit stall where their pit crew will service the car, which can include changing tires, refueling and other adjustments.

SAFER barrier – The Steel and Foam Energy Reduction (SAFER) barrier is a special type of retaining wall found at racetracks. Most racetracks on the NASCAR circuit have had concrete walls which, when a driver hits at a fast speed, can injure the driver. The SAFER barrier is basically another layer added to the concrete wall on the track side of the wall. It’s made of flexible steel and foam which can absorb the energy from the impact of a racecar and disperse it in a way that allows the drivers to be much safer in an accident.

Slide job – This is a common passing tactic in dirt racing that has now made its way into NASCAR. To perform a slide job, the trailing driver intentionally accelerates too far into the corner to the inside of the track in order to make the pass on their opponent in the middle or on the outside of the track. The driver must then brake to slow the car down and get it to turn, so to ensure the car they just pass doesn’t pass them back, the driver “slides” up the racetrack in front of the driver they just passed.

Tight – When a car is tight, it means that the front of the car lacks grip, which makes the car hard to steer in the direction the driver wants.

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