Using roof top tent you need consider

If you want to use a roof top tent successfully, you must have a third-party  roof-rack system. Which is installed on your car. Why can’t you use the  factory-installed roof rack? On the lighter end, roof tents weigh around 150  pounds and most preinstalled roof bars are graded to hold exactly 150 pounds,  not more. If you place a roof top tent on a factory-installed roof rack, there’s  a good chance you’ll not only break the rack but also damage your car.

Even if you have a good third-party rack installed on your car, the weight of  the tent can affect your car in a host of other ways, such as, the most obvious  is substantially reduced mileage .