This guide will help you quickly level up your Racing XP
Once you get there head for the Kart track, but skip the karts and use your own car, whatever it is.
The game doesn’t limit the track to only carts to you can whip around it how ever fast you can in your own car, for me that’s 15 seconds for some it ll be faster and some slower but still the fastest in game. If you run out of gas just hit the pump next to the track and there’s a tuning shop there too. Took me about 5 minutes to get to level 5 for the second police car.