When purchasing upgrades for your car, focus on those that are in the "Performance" category. Almost all the upgrades will increase the damage your engine takes. Purchase the Performance upgrades that do less damage than the others first. Upgrades to the intake system or the engine internals are recommended; the first levels are cheap and should be purchased as soon as possible. You will eventually reach a point where you will not be able to win any races without a NOS system. It is fairly expensive and requires a few upgrades in order to get the most out of it. Use the NOS in every race for an added bonus. The lighter the car, the faster it travels. Try to reduce its weight under the Chassis category. There are three upgrades you can purchase here. Get them before adding other performance enhancers to get a better boost. Unlike other upgrades, the Grip category allows you to immediately purchase the best tires. The best ones cost just over $500 and are worth it to get the best out of your car. Keep the aesthetic upgrades to a minimum while spending your money on more useful upgrades.