Now if he just had an excess amount of money and wanted to buy his mom a car, cool, that's a great thing to do... but for parents to come around and say, "I took care of you for X amount of years, so you owe me. I'm coming to collect on my favor now." I'm sorry, it doesn't go like that. When you have kids, you have them with the expectation that YOU chose to bring them into the world, and thus the responsibility is on you to take care of them. They are not your burden mules and they don't owe you anything back, but if they do something for you, great. Also, parents are supposed to be the responsible one, so why doesn't anyone bring up how foul it is for a grown up to come to their kids to buy a luxury item and then when the going gets tough and they can't pay, just quietly let the loan shift to their kid and destroy their kids credit? Is that proper parenting?
Now if you know your mom just went through a tough patch at one time and that messed up her credit, but now she's back on track and stable, then you might consider it, but if she has a history of not handling her financial priorities, even if that is your mother, nah. We're in a recession and who knows how the economy will look in the next few years. What if she loses the job. That's on you to pay up. What if you lose your job after that? Both of ya'll are done for. Nobody 'needs' an SUV. If you have sufficient savings to where you can give her 10,000 and not think twice about it, coo, do that as a favor to your mom, but if you taking on those payments will have you stranded, you got to be responsible no matter what.