For engine nerds, you should check out Automation - The Car Company Tycoon Game [1]. It is basically a car builder simulator where you go through every aspect of developing a car - chassis design, suspension, engine..
I spent hours tuning and building exotic engines. 6 liter turbo inline 3? 1 liter NA V12? Only your imagination is the limit.
[1] https://www.youtube.com/watch?v=xQpfvliszx4
Bonus: You can export your vehicles directly in BeamNG.drive and test them on the track.