In Rage 2, your car can be a deadly weapon if only you take care of it accordingly. To use the car in battle, you will have to constantly repair it, upgrade it and supply ammo. On this page of the guide for Rage 2, you will learn where you can buy ammunition for the vehicle.
The traveling merchants and vendors in the city have car ammunition in the offer, the cost ranges from 1 to 5. It's hella cheap, really, and the ammunition for the car wears out very quickly, so it's best to buy it a lot.
Obtaining Raw Materials
When exploring the world of Rage 2, you will find many sites with loot. Explore these places and collect ammunition scattered by enemies.
Remember to always have a lot of ammo in Rage 2. If you run empty, someone might quickly kill you.