Hi there
These are really for overland expedition type 4x4’s and will add a lot of weight high up on the car increase your fuel consumption dramatically, but you’ll never pay for another hotel!! LOL
As has been said a sturdy roofrack is a must or three strong roof bars… Most tents weigh around 50 to 60 kgs so they need to be well fixed…
You have two types of tent the canvas fold out type… these take up les room of the roof so you can add other items, but once wet take a good while to dry out and you shouldn’t really fold away wet…
Second choice is the hard fibre glass type, like a giant roof box, that winds up with a crank. This is the type I had… goes up in seconds is very comfy… and folds away almost as fast. Just about the only down side is that it takes up the whole roof.
Mounting these items is fair operation and really needs at least two people… manoeuvering 60kg is not easy, so once it’s on it’s on!!! Off the car they are huge pieces of kit to store..
I found mine brilliant it was a Maggiolina Adventure and we used it a lot, including an 800 km trip across the top of the Pyrenees…
There are cheap models on the market but I’d suggest a second hand model of a good brand.
Eezi Awn or Howlingmoon for the canvas fold out type
Or Maggiolina by Autohome or James Baroud for the hard shell type…
A good brand will be easier to sell on once you have had a few years fun!!
Cheers
Gareth