Hi - I'm a retired vehicle engineer.
I started out as a design engineer, then became a 'specifications clerk' - which meant collating every possible dimension and detail that body-builders (and those wishing to modify vehicles) might conceivably need (the maxim was if they could find out by legitimate means - ie buying and analysing components - then we would provide the information in 'manual' format).
This meant that I learned lots and lots about things that most folk don't know exist. If only I had kept a copy of that manual!
Next I moved to vehicle testing (of prototypes and experimental vehicles) where I dealt with both passenger and commercial vehicles (including military vehicles).
Then I moved back to design, working on systems such as transmission and braking. I even represented the company on legislative committees when the EEC were trying to standardise things across Europe.
Finally, I moved into component manufacturing and supply (brakes, then transmissions and steering).
As I stated, I'm retired, but I retain my interest in vehicles - especially old ones and military vehicles.
Any questions then I'll try and answer without incriminating myself . . .