The penis.
Typically a passenger vehicle modified to run and/or accelerate faster. The term may be used generically to apply to any car, truck, or motorcycle (et al.) modified for increased speed and/or performance. It may also be used to specifically describe and refer to modified cars from the original (or traditional) era of "hot rods", post World War II and prior to 1960.
To modify a vehicle for enhanced driving performance, top speed, and/or to accelerate faster.
Human flesh.