Car modifications are loan modifications that help you better afford your monthly payment. If the idea of a loan modification scares you, then you'll be relieved to know that many people go through this process and it helps them fix their credit and avoid repossession.
Car modifications involve several steps. First, you have to be behind. Lenders don't negotiate loan modifications with people who are making their payments on time. If you're keeping up right now but you fear falling behind in the future, and currently your credit is good, you might choose refinancing or loan consolidation instead. Or if your car is worth more than you currently owe on it, you could simply sell it to pay off your loan and purchase a car that costs less with smaller payments.
But if you are falling behind and you're having financial difficulties in keeping up with your car payments, then you're the perfect candidate for car modifications. Your credit doesn't matter because it's expected that when you're in a hardship situation you're going to have credit problems. If you try to refinance with poor credit, you either won't get the refinancing loan or the interest rate will be higher than you expect making it not worth your time or money to do so.