Our E-Niro is the dirtiest car I have ever owned.
That's a feature of cars that are aerodynamically designed. The shape is made so that it holds on to air as long as possible. Hence the flat bits on the side of the rear bumper, more obvious on Leaf and Ioniq The back is then as flat as practicable, with spoilers added to the top of sloping rear glass to mimic a flat back. This pulls air onto the back of the car and brings dirt along with it.Took me a while to find the little handle inside the tailgate so that you can pull it closed without touching the filthy outside bit.