Not long after entering Season 5 you will be given the chance to own the McLaren F1 GT, once you have this car start a race with the following:
Race Type: Race
Vehicle Tier: Tier Four
Rounds: 1 Round
AI Drivers: Very East
~Advanced Options
Grid Order: Random
Damage: Visual Only
Flashbacks: Unlimited
~Track Selection
Location: Indianapolis
Track: GP Circuit
Laps: 2 Laps
Vehicle Selection: McLaren F1 GT
Now once you enter the straight away at the end of your first lap you will easily be able to break 230mph/370kph
Here's a video