However, despite the vintage appearance of the cars, often they conceal underpinnings more closely related to modern NASCAR entries. Tuned V8 engines of more than are common, especially in the American cars, and the cars are often created especially for this race and usually ineligible for true vintage events elsewhere. Even less modified cars often have modern disc brakes at all four corners and coolant upgrades to help them survive the punishing course. Six-point roll cages, racing seats, fire-suppression systems, and fuel cells are required in most classes. Drivers and navigators are required to wear two- or three-layer fire-resistant suits, HANS devices, and label their helmets, uniforms, and respective sides of the car with their blood types and allergies.