Problems, Crashes and Errors of Car Mechanic Simulator 2015 TODAY

If you're experiencing the game crashing on Xbox One during gameplay, then consider the following: Change the difficulty mode from Normal to Expert or vice versa.
Save the new file on the new chosen difficulty mode.
Keep playing and saving the game only on the new mode.

The best car to repair is the Atom Renton (2006), which can be sold fully repaired for about 80K.
Before attempting to repair any car, you need to purchase the following upgrades that will increase the efficiency of your repair job: Welder.

Find suspension and fluid jobs, they're usually cheap and quick, and will help you build your bank back up.
Or take a bigger job, strip the car and sell the parts to finance more lucrative jobs, and then rebuild it when you have plenty of cash.

Even though the game uses fake vehicle makes and models, the parts on the vehicle are accurate to where they would be on real vehicles, and in relation to other parts on the vehicles.
This is true whether you're working on a 1970 V-8 or a 2018 electric car.