I think it's important to add this one because it's free and doesn't even require previous planning, so it's very hard to argue that you couldn't do it instead of driving drunk.
(Although keeping a blanket in your trunk makes it a much better experience.)
Some states like California you can only get a DUI if there’s evidence you moved your car, but in other states it’s a lot less clear - and you can be charged with any appearance of intent to drive, like sleeping in the driver’s seat.
Not to mention the possibility of getting a trespassing charge in a private lot overnight.
There are better alternatives than drunk driving, but sleeping in your car isnt one of them.
Plus, I don't know how American cops work, but hopefully they're less likely to stop and breathalyze a dude sleeping in a parking lot than a guy on the road at 4 AM.
Also, now that I think about it, American cars are huge, if you put the seat all the way back is your body you going to be even visible from the road?
No but your car will be, which will probably be investigated. If you are on the side of the road you'll definitely be investigated and for sure get a DUI because they'll say you drove there and parked. (Also definitely a no-go on highways/freeways).
If you are in a parking lot cops will usually scope out a car, especially if you are parked away from other cars and then they'll wake up and tell you to move. Then you'll say "I'm drunk I can't drive" and then that's where all of the problems start. If you park near other cars (perhaps late night workers) they'll probably call the cops or call a towing company because you aren't allowed to park there and sleep overnight (another reason all these gigantic stupid surface parking lots are so useless).
There's just way too many problems with this strategy.
I've slept in my car in night clubs' parking lots several times and have never been bothered, either by the owners or by the police. I've also had friends follow my recommendation (well, more like pleading/pushing, since they were insisting 'noo I'm fine to drive') without trouble. Likely a difference between laws/customs in different countries.