Greetings, mrdpunto, and welcome to GTPlanet!
Yes indeed, people do use the ZZII. It's widely regarded as the fastest car with no door numbers in the game. However, it doesn't quite qualify as a street car since it has some racing parts installed, and you can't use it in the "normal car" races (PD Cup, Trial Mountain Enduro).
Try these for the 900-hp or so upgraded car:
* Springs 15.8/13.8
* Ride Height 60/64
* Bound 5/6
* Rebound 8/8
* Camber 3.5/1.5
* Toe -0.5/1.0
* Stabilizer 5/5
* Brake Balance 15/17
* LSD Front 10/25/15
* LSD Rear 13/35/25
* Downforce 1.00/1.01
* ASM 0
* TCS 0
* VCD 25%
* Tires T4/T4
* SetAt 3.960
* AUTO 28
* Final 3.200