Ok here's a story of my old Cutlass I loved but ended up hating thank god I wrecked it lol! Late '70s early '80s I was working for Kroger and it was summertime so I left my windows cracked etc etc right. So one of my best friends (who I actually just got off the phone with to relay this memory) and another friend shot a rabbit at the ranch and stuffed it under my drivers seat lol! It took about a week to figure out and find the rabbit, uhhh that smell can't you smell that smell
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I can top that.
Thankfully not with my car... but a friend of mine and I went fishing for blues on a charter off the jersey shore, and we used picked up some calamari to use as bait... I'm not the fisherman, so don't fault the technique if it's wrong. I simply went for a day out on a boat and the beer.
So we get to place, get out on the fishing trip and when we're 45 minutes out and go look for the bait, he realizes that he left the plastic bag in the trunk. This was a little pos Audi Fox, can't even remember the year, probably early 80's. Well you've got no idea what calamari smells like when it has been left inside a hot trunk of a car for 8 hours under an August sun.

Needless to say, after countless washings of all the rugs and hosing out the back of the car, you could smell it months later! Her got rid of the car, and we still laugh about it.