First You Need This Car:
https://www.gta5-mods.com/vehicles/bugatti-veyron-grand-sport

OR THIS CAR :

https://www.gta5-mods.com/vehicles/bugatti-veyron-2009-add-on-replace-auto-spoiler-animated

Features:
+REAL Top Speed 431 km/h

+ULTRA REALISTIC Bugatti Veyron Super Sport Acceleration (SIMULATION TYPE)
-------------- In Game ----------------------------
0 - 100 KMH : 2.453 Second
0 - 200 KMH : 6.703 Second
0 - 300 KMH : 14.42 Second
* ALL RESULTS ARE STABLE BECAUSE ALL IS TESTED IN AIRPORT

-------------- In REAL ----------------------------
0 - 100 KMH : 2.5 Second
0 - 200 KMH : 6.7 Second
0 - 300 KMH : 14.5 Second

WHY ULTRA REALISTIC AND SIMULATION TYPE ?
Here is Source: http://fastestlaps.com/models/bugatti-veyron-16-4-super-sport

+REAL AWD (4 WHEELS DRIVING)
+ULTRA REALISTIC Brakes (SIMULATION TYPE)
+ULTRA REALISTIC Steering (SIMULATION TYPE)
+ULTRA REALISTIC Off-Road Traction Loss (SIMULATION TYPE)
+ULTRA REALISTIC Off-Road Losing Controls (SIMULATION TYPE)
+ULTRA REALISTIC Suspension Improvements (SIMULATION TYPE)
+ULTRA REALISTIC Engine Damage and Deformation (SIMULATION TYPE)
+ULTRA REALISTIC Preventive Skidding System On High Speeds (SIMULATION TYPE)
+ULTRA REALISTIC Wheel Slipping 0 - 80 kmh Section (SIMULATION TYPE)

Changelog:

Version 1.5
Reworked Top Speed
Reworked Steering
Added Another Bugatti Veyron Car Handling

*Please Read Readme Before Istalling.
*Enjoy Driving !