Grand Theft Auto V (GTA 5) allows players to modify their vehicles in several ways, including performance upgrades, visual customization, and adding new features. Modifications can be performed at various garages and auto shops in the game, and some can also be purchased through the in-game internet.

Some of the popular modifications in GTA 5 include:

Engine upgrades
Suspension modifications
Brakes upgrade
Exhaust systems
Paint jobs
Rims and tires
Lights
Spoilers
Hoods
Grilles

It's important to note that while modding can enhance your gameplay experience, it may also affect the game's stability and can cause issues with online play. Additionally, using mods may be against the terms of service of the game and could result in a ban.