I was thinking about the car last night also and then I remembered something, my good friend J's car.
I love J, she's funny and generous. We make an odd pair, she is 4'11", I'm 5'11", she is Asian, I'm blond with freckles. She can eat two big Macs, biggie fries, giant glup and still weigh 89 lbs; me, I can gain weight on a kid's meal. We have a great time together but I can't stand riding in her van! She mucks it out maybe twice a year; yes, mucks
She has four kids and when she was driving them all around, the car was a health hazard. Half eaten hamburgers spilled soda, pizza boxes with half a pizza, dirty underwear. balled up socks, used tissues and napkins, fruit, you name it, it was there. I have helped her take out two full trash bags of stuff that needed to be thrown away and there was sill at least two loads of laundry in the car.
The point of this is that it did smell in her car, I would ride like a dog, with my head out the window. But...it never smelled like a dead but once living thing. We live in a humid area and she parked the car in the sun. One time, I saw her same model car in a parking lot and to be sure that it was her car, I smelled the car and yes, the odor was there even with the windows up and car locked! It smelled like a trash can but not a dead body.