I used the 1080 Matte Metallic Silver on my Mini Cooper S and it has held up very well for being a low car. There are a few small chips in it but no more than 3-4 and it has been about a year now. My problem is if I don't keep the car clean every week the dirt/road grime will start to stain the horizontal areas of the car. On a side note the film is a little on the thin side so rock chips will happen at some point.
Also you could tell your customer to back off from the car in front of them on the interstate, this will help tremendously.