I have an extended cab pickup truck, so when I sleep in my truck on trips I move over to the passenger seat and push the seat back as far as it goes, and recline it as low as it goes.
Wool clothes and wool blankets and I’m pretty toasty.
I sleep behind the wheel in a 1980s army oversize mummy bag with the zipper down the middle, with a sheet or blankets inside of it depending on the situation.
The middle zipper makes it easy to stay warm and read or play music and think, I sleep at the wheel and when refreshed I turn the key and go, after getting in 2 hours of driving I stop and make coffee and cook some breakfast.
I’m a hard-charging driver and prefer to drive at night, so while I drive during the day, I also drive as long as I can at night which leads to little sleep, there is never a time when I feel like spending money to grab a few hours in a motel, and besides, I like to sleep in interesting places, like snowy mountain passes or at Mt. Rushmore if I am in that region, which I will go out of my way to find.
When I’m out and about the country, I’m looking for adventure, and getting lost in the wind is a goal, but even going from A to B in a hurried Interstate Highway cross-country drive I still just pull onto a side road to sleep.
For me, the car is a form of camping and I really enjoy the independence of being self-contained and alone with no one knowing where I am, or what I’m doing, seeing new areas, seeing only strangers, using laundrymats when needed.
I think it is the closest I can get to my years of drifting around by hitchhiking when casual work was easy to find and going to a bar just about guaranteed a girl and a place to shower for a few days and free beers from the pool table or arm-wrestling.
The pre-immigration America was a very interesting place and easy to move around in, if you want a sense of the pre-immigration America, read “A Walk Across America” by Peter Jenkins.