Repair Tools

Repairing parts is actually a very advantageous ability. However, the law of averages seems to be completely askew with this system. Even at 90% you'll often be amazed at the poor results. You'll also be spam clicking like crazy if you have a lot of parts to repair. All in all, it is my last thing to upgrade.

Your best bet is to just use the Sell Junk option in your inventory to sell stuff that isn't any good. Then collect the old beaten up parts until you have 90% as your base repair chance. Just don't bet on that average. Then you can try to repair all the old stuff you've collected. This will give you a major leg up when it comes to buying cars at auction and rebuilding them, as you'll have a stack of spare parts in your inventory that you didn't pay a dime for.

Some parts cannot be repaired. It is also true that you'll have to repair parts several times to get them to 100%. And if you fail once on a part it will be damaged and you will not be able to try to repair that part again. Repairing any part to 100% makes it the same as a newly bought part and the client will be billed for it as though you purchased it in the case of work orders.