It's the fastest Hp/T ratio vehicle with ~289 Hp/T Followed by the Motorcycle (I think) with ~83 Hp/T

Really funny to use!
When test driving the Zenith, a unique time trial race is available accessible by a highlighted green circle with a checkered border. The race takes place at the test track of north of the Garage, where you can race yourself to get the best single lap time (your personal best time records are saved).