How to Mod Cars in GTA

Accept the mission entitled "Cesar Vialpando" from C.J.&'s brother, Sweet. The mission will require C.J. to participate in a low-rider competition. In order to prepare for the event, you will be directed to the Loco Low Co. to install hydraulics on the car, introducing the ability to modify cars in the game. Successfully complete the low-rider challenge at El Corona, involving moving your car to the music beat, and you will finish the mission. Once the mission is complete, car modification is unlocked.

Choose the car you wish to modify. Most vehicles in the game, excluding boats, flying vehicles and city vehicles like police cars, can be modified. Once you have chosen the vehicle, enter it with the "triangle" button.

Drive to a car mod shop. Shops are indicated by a red wrench icon on the mini-map and pause screen map. Note that certain shops will only service specific types of vehicles, such as Loco Low Co. only modifying low-riders. New mod shops will be unlocked as you progress through the game. Once you arrive at the shop, the garage door will open for you to enter with your vehicle.

Modify your vehicle. Upon entering the shop, the mod menu will automatically open, presenting you with the available options. Car modification options are both cosmetic (such as paint jobs and hood scoops) and performance-based (such as nitrous boost, hydraulics, bass boost and off-road tires). Different modifications will be available at different shops. All modifications will cost in-game currency, and are only installed on the vehicle you purchase them with. Save your newly modified vehicle in one of your garages after leaving the mod shop, as changes will not be saved otherwise.