This is definitely an age thing. I once had sex in the back seat of a Morris Traveller in the middle of the afternoon in the parking lot of a pub when I was 19 and was extremely proud of myself but I had to get into some kind of yoga like posture with my legs pulled up and overlapping to do it as I'm 6'4" but it was great. Now at 66 I can't fully bend my knees so good luck trying that again.

One other time I was getting head in the back seat of my car in the Berkeley hills at about 2AM when a police man shined his flashlight through the window and said, "Are you alright, sir?" I had to restrain myself from saying, "Doesn't it look like I am more than alright?!" LOL