I keep cars till they really won’t go any more. Current car is from 2006, with almost 300k miles on it.
Start saving a car payment every month in a separate account. Essentially making a car payment going forward, and when you have enough in that account, then buy a car.
Wrap the whole thing firmly with a towel, something thinner and long, so you get multiple wraps. Then put it in a vice, very gently - just tight enough to hold it. Or let a person hold it.
Then use an impact driver to get it loose. If you use a cordless driver, use quick, short bursts. Like 1/4 second at a time.
Double check whether it’s a left- or right-hand screw.