Get Nitrous Boosts
In order to geed the Nitrous boosts, you have to get the third level of a car. Once you have the third level car, for instance the Last Truck, go into a race. Then, click the horn button. You should hear a WHOOSH. (You get a limited supply, so use it wisely; around 5) This really will help you break those neck-and-neck races on the straightaways