As title, I'm not sure if this was suggested or it's in Mike's plan for the mechanic, but I can't find any topic that's related to this.
So I want to suggest that Mechanics can fix cars even there's no driver inside to offer service. Being a mechanic but can't fix his own car is pretty much unrealistic. I know you will say use the Engine Repair Kit, yeah, but what if you already used and there's no gas station around.
Or maybe we can modify the number of limits to hold more Engine Repair Kit, make it to 3 or something and that would be nice.