I've put K&N filters in my last 4 or 5 cars over the last 20 Years or so. Can't say they improved mileage, but never had a problem with any of them.
And the only time I might go "Off-Road" with the HHR would be if I fell asleep!

 

I have used K&N's also for over 20 yrs. And I have never had a problem with them, and we even use the at work on nthe diesel engines we build. One thing I always do whether it is with a new filter or one that has been cleaned is to lay the filter on a piece of news paper overnight (longer after re-oiling) and let some of the oil wick out, before I place it in the vehicle.

 

Filter on my pickup is from 1990.....always used them on my race cars also, never saw this "dusting" I hear about. Makes me think somebody didnt check and seal ALL openings...I even run an o ring on the hold down nut....you'd be surprised where air can sneek in.....all you have to do is follow the stain.....the snorkle type cleaners were prone to leakage unless you took care at the mating surfaces, either with double gaskets or making thicker ones..the store bought types are too thin and have a tendency to 'walk', creating leaks.On snorkels take a small rubber hose and split it( vacuum)run it around the bottom of the sharp edge of the air cleaner base and seal the ends.This way the housing bites into the rubber instead of the gasket.