My V40 got some stone chips on the front bumper, especially when I was driving in Sweden, but it got replaced after I hit a deer. There are no stone chips on the present front bumper yet.
It also got a few small marks on the rear bumper, probably caused by our pram or suitcases striking it lightly during loading or unloading. Thus, I think the coating on the bumper is relatively weak. I repaired the marks yesterday with a paint kit from Volvo, spending two hours on repainting, before achieving a satisfactory effect.
You can't avoid that if you drive fast. I'm sorry about that. the most way to protect as must as you can is coating color with glass coating or teflon coat. It can help for a little but mostly depend on environment on the street and driving style.