Easily the best car in GTA Online.
Ferrari Enzo (front) and Koenigsegg Agera R (back).
A speed of 230mph, 20 less than the Adder and 10 less than the Entity XF. That doesn't make a difference, as the top speed possible online with a fully upgraded Adder is 143.64. That was tested at the airport.
Try using any super or sports car off road, and feel your controller vibrate and rumble. Try this with the Cheetah and it's smooth, and drives easily. I tested this with high end wheels.
How good are the other cars? I used to love the Adder, it's good until you want to brake and go around the corner. If you hold down the left trigger and pull the analog left or right with the Cheetah, you go straight round without spinning out or smashing into a pole.
The Cheetah seriously is the greatest car on GTA. I'm talking about the fully upgrade level four engine, brakes, transmission, suspension and turbo charged one. I've not use the stock upgrades, so I can't speak for that.
All of my cars I've ever had in my garage (replaced many) have been fully upgraded. Such as the Adder, Entity XF, Infernus, Vacca, Bullet, Voltic, 9F, Carbonizarre, Rapid GT, Sultan RS, Banshee, Comet, etc.
Anyway, none work for me as well as the Grotti Cheetah!