you can't.
There is no such thing as a Hover Car for GTA IV. It could be a mod or someone has told you false information.
NO
yes
hold triangle in the car
washes ur car and cleans it
Steal a car from the streets and ram the car that you flipped
There is no Ferrari in GTA IV. There is a car called the Turismo wich is based on the Ferrari 360
No, there is not a Ford Mustang in GTA IV. You can mod your car using a computer to get a Mustang but otherwise there is not a Mustang in GTA IV.
Ford Thunderbird
No, There isn't one in GTA IV.
There is nu Bugatti in GTA IV, only if you play it on the PC you can download a mod wich cganges an ingame car to a Bugatti
There is nowhere in GTA IV that you can purchase a vehicle.