The NASCAR Unlimited Series cars are depicted as the most powerful and technologically advanced cars on the planet. They have very unusual design and features, such a very large and low profile body, a built-in rescue racer (except for the experimental XPT-1 that Mark drove in the thirteenth episode, "All or Nothing"), power-ups such as boost rockets and atomic fuel engines. This gives them an enormous amount of power, making them the fastest cars in the world.
XPT Racers :
The XPT Racers are the cars used in the first season until the nineteenth episode, "Rumble", when the NASCAR commission decided to replace them with the Nitro Racers. These cars share the new engine of the experimental prototype XPT-1, but they don't share the design. They have a distinctive look, featuring a very long and wide body and very small cockpits compared to the size of the car. However, they are no taller than a normal car, making them look very low-profiled. A side view of the car shows excellent aerodynamics, thanks to a very low cockpit. The XPT Racers have front placed engines, thus having huge hoods and rear placed cockpit. This aspect is seen on all cars, but especially at those driven by Diesel "Junker" Spitz and Megan "Spitfire" Fassler. The most unusual car is the one of Steve "Flyer" Sharp, which appears to be rear-engined due to the two boosters behind the cockpit. These cars have been designed from scratch by Megan Fassler. The NASCAR decision to replace the XPT Racers was a major shock for all Fastex drivers, who had built strong relationships with their cars.
Nitro Racers :
The Nitro Racers are the cars introduced in the last seven episodes, after the NASCAR decision to replace the XPT Racers. Unlike the introduction of the XPT Racers after the first season, the Nitro Racers were completely different from the previous cars, featuring all-new design and engine. They are all-round larger, having two seats and even rear seats as shown in their first episode, "Crash Course". Their most important upgrade is the brand new high flux fusion engine, meant to squeeze the last drop of power the atomic fuel can give. Due to the increased size and new design, inspired by NASCAR Truck Series, they appear to have massive rear placed engines. Most probably those are the additional high flux units, since the real engine is still under the hood, as the crew chief Douglas "Duck" Dunaka is seen making repairs under the hood and not behind the cockpit. These particular cars are depicted as being better in every conceivable way than the XPT Racers, thus becoming the fastest and best cars in the world. Beyond the new design and engine, they share the same features with the XPT Racers, such as rescue racers and boost rockets.
Rescue racers :
The rescue racers are one of the most iconic feature of the NASCAR Unlimited Series racing cars. They are activated by a special button to prevent injuries in case of accident. They eject from inside the car after the roof of the cockpit blows up. They represent the futuristic and safer version of self-ejecting chairs. In official races they are only for securing the driver is safe and is prohibited to race in them. However, in nineteenth episode, "Rumble", Flyer is seen competing in his rescue racer, as it was an unofficial race.
Simulator cars :
The cars in the simulator are shown only until "Rumble", as they were only XPT Racers with simplified look. Their design is very simple and straight, as they are only meant to reproduce the virtual reality the drivers need to train with. Other than looking simplified, they share the exact same features, including boosters, random power-ups and rescue racers.