i agree with noise - it really doesn't sound like he could handle the sudden costs that owning a modified car can bring. Also, I'd never counsel someone to go into debt over a depreciating asset, so borrowing the money, to my mind, would be a bad idea.
I think sell the car, pay the workshop, learn the lesson, get on with life debt-free and still with the ability to get back into the import scene at a later date.
My 2c.