Slang a car that's been reconstructed or modified to increase its speed and acceleration.
Typically a passenger automobile altered to run and/or accelerate quicker. The expression works extremely well generically to utilize to any vehicle, truck, or bike (et al.) altered for increased speed and/or performance. It would likely also be used to particularly explain and reference modified cars through the initial (or standard) era of "hot rods", post World War II and before 1960.
a motor vehicle customized to increase its speed and acceleration