To make this process easy, make sure your inventory is empty, there should be nothing in there, as any body parts removed/replaced should be back on the car and the trashed ones sold for scrap. This is a case where having a pen and paper with you will come in handy. (However, I still personally paint the car a new color to something more attractive if it's an ugly color or repainty the 'factory color' if it's something decent and I just want the car to look better.) Simply restoring/replacing the damaged body panels will bring it to 100% and get you the most you can from that aspect of the final value. Repainting the car, painting it another color, or putting the 'tune shop' after-market parts/rims on it don't increase the final sale price either.
The most profitable thing to do is to restore the car to 100% both body and engine, not restoring/replacing even one part can cost thousands of dollars in the final sale price. sell the shell for $0) then repair all of the parts and then sell everything (repaired parts, parts that couldn't be repaired/were damaged by repairing.) The only reason to buy and restore a Maluch is for the 'completion' of collecting all of the cars in the game. It's honestly a lot more profitable to buy the Maluch, strip it down, scrap the body (i.e.
FWIW: Buying and repairing the Maluch car isn't profitable, the money you get from a 100% restored Maluch falls short of the average winning auction bid and the cost of repairing/replacing parts.
