Used cars depreciate very slowly on average (if something expensive breaks you are SOL though).
New cars lose a lot of value the moment you buy them, and then start to follow the used-car curve.
Everyday cars with a reputation for reliability lose their value very slowly. Luxury cars lose their value very quickly at first, but then slow down a lot.
Buying and selling to/from private parties saves a lot of money, but adds a lot of hassle.
Campers (and I'd imagine RVs) are much the same. Once they hit 15-20 years old, as long as long as the interior is decent and you keep them waterproof, they won't really lose value. Replacing components like the fridge or water heater is pretty cheap and simple if you can come by the parts.
New cars lose a lot of value the moment you buy them, and then start to follow the used-car curve.
Everyday cars with a reputation for reliability lose their value very slowly. Luxury cars lose their value very quickly at first, but then slow down a lot.
Buying and selling to/from private parties saves a lot of money, but adds a lot of hassle.