Two things really need to change: first, you should be able to make a bit more money from buying and selling vehicles. It's basically zero-profit busywork. The game gives false, misleading figures for how much you've spent on parts - add it up yourself and you'll see. The only "profit" comes from selling the old parts, and you make a couple of hundred bucks. Second, you shouldn't be able to accept orders that you don't own the tools for. You can't buy cars you can't work on, so why allow orders?