I've slept in the back of a truck many a nights, and tried a SUV a time or two.
Even had some trips were I've pitched a tent and couldn't sleep because of back pain, and wound up sleeping sitting reclined in the passenger seat of the vehicle just fine.
Pros are quick set up time, just pull in and your almost done. Doesn't necessarily have to be in a designated campground, if you can find a place you feel comfortable parking, and it's legal. Have Heat and AC.
Cons - stinky morning breath, moisture (in my experience the windows have had to stay cracked no matter the weather). Have to be careful if you run the engine too much, don't want to run out of gas or get carbon monoxide poisoning.
They do make some tents that attach to the rear of a SUV or set up on back of a truck. With those I don't suppose you could run the engine any.