The XP factor is very important for gameplay however you need to earn it.

I find drifting earns XP faster than anything, but you need the right car.

First I personally love to use the Monster Energy Falken Tire Mustang that you get after beating the drift pro Vaughn Gittin Jr .

If you have trouble use the second best drift car (and also the car I beat him with) the Nissan 350z and drift at London Millennium drift event.

I race 99 laps, but that's a long time!