Can you trade in a used car for another car if you are still making payments on the first car?

Yes you can, but you have to owe less on the car than the trade in given. In other Words if you owe 2,000 on the car and they give you three that means the loan on car 1 gets paid off and you have a 1,000 towards the price of car 2. But if you owed 5,000 on car 1 and they gave you 3,000 you would still have a balance due on car loan 1.