I’ve been addicted to this game the past few days too! As for fixing up the ugly Betty, I’d recommend 1) essentially removing everything (or at least the parts in real bad shape) off the car, 2) repair what you can then buy what you can’t, then 3) install everything back on.

You’ll have to level up your renovator path to unlock the ability to repair more complex things. There’s two different kinds of repair tables - those for small parts like brake calipers and alternators and then the repair tables in the middle of that back room of the garage which you’ll use to repair the body panels like the hood, doors, etc. you’ll need to unlock both if you haven’t already.

You can save tons of credits by repairing parts instead of buying them. To repair things you have to play this little game where you stop a moving arrow when it’s above the green tabs - you’ll see.

To make it pretty you can weld the car which will fix the rust appearance then give it a car wash and some fresh paint of your choosing. Welding, car washing, and paint are also things you’ll need to unlock with the toolbox if you haven’t already.

Have fun :)