I never used cars in game, what advantages they can give me and when to start thinking about get one ?

Vehicles are hilariously OP, but there’s a low to moderate entry barrier.

If you’re able to find one in ‘working’ order early game, you’re set. Strictly speaking, all it needs to have is a working engine, fuel in the tank, power in the battery, enough wheels and a seat with working controls. You can look at them (x) from a distance all these things, but usually it’s easier to [e]xamine them up close and look at the stats. An alternative option is to try and find a working electric car, which might have working solar panels and doesn’t need fuel.

Midgame, if you have sufficient skills you can scavenge parts from mostly broken cars to build a single working car. Easy fixes is stuff like changing tyres or swapping a new battery in. Harder stuff might be replacing a broken seat or controls, or mending a faulty engine.

Endgame, you can weld all sorts of useful stuff and turn a vehicle into a mobile base. Solar panels can provide power for cooking, crafting and repairing your vehicle. Many players do this, since it allows them to be mobile but have access to their base at all times.

In terms of advantages, vehicles are super powerful at killing things and providing shelter. Although if you want to start running things over, you need to make sure that you’re wearing a seatbelt, and the part of the vehicle you’re ramming with can hold up to the task. For example, electric SUV’s are made of very light frames and don’t last very long at all if you ram them into everything.

just about anything, vehicles can grant near-immortality with enough effort, the amount of trouble you’re willing to go to is the main limit.