If you are a gearhead , you should major in Mechanical Engineering is school. I did and really love my job (most days). While in school I participated in SAE (society of automotive engineers) student design competitions, basically got to built little race cars with other folks money!! You gotta love college!!
Now 20 years later I am working OT to finance barcket racing my 73 Dart Sport, wishing I was back in school.
Bob
PS: most engine designs are inefficient , solar cells on spacecraft generally run around 25-28% efficiency while are internal combustion engine less than 20% (as I remember it from over 20 years ago).