Don't forget the awesome Car Mechanic Simulator 2014!
But seriously, its an awesome game. It is probably closer to a puzzle game than an actual simulator but it is really well done. It has a realistic depiction of parts and while it is not as in depth as it could be, it does a great job of showing you how the parts work and what parts interact with each other. Definitely worth grabbing, and even better if you can get it on sale.
If you're interested in that, you should take note of Automation.