4 suction cup vs 2 suction cup?
I am pointing out the max load on each Avenger cup which is rated 2kg.
It's better to be safe than sorry especially if you are doing this for other cars.
An Avenger can handle more than only those 2kg rated by Manfrotto. To be precise: those 2kg are only for load on a wall with a distance of 30cm. So it is not comparable with a load that pulls/pushes the suction cup on a flat and even surface.