We used to call my bffs mom's car the interrogation room. Every time we would get in the car she would ask us what we plan on doing with our lives (in a much nicer way, she's a very sweet woman it was just a lot at 18). We all got our drivers licenses to avoid this situation.

The solution is to avoid bringing him around your parents. Your parents sound like they've been doing this forever, so you can't expect them to change. You CAN avoid putting your partners in that situation. If your parents ask why they haven't met your SO or why they haven't seen him in a while you can take that opportunity to talk to them about the insane interview questions.