K&N filter for replacement ?

Like I said before, correct me if wrong,(hopefully I am here to learn like everyone else) the most restriction is at the throttle plate bore. The filter box etc are way oversized in comparison. Some new cars are promoting 100k air filter life. I plan on sticking a new OE in every 50k, and that should be all I need to think about on the Prius air filtering.
As for environmental savings, I shudder to think of all the oil mess people are making with washing and re-oiling. I have done it with my lawn mower which has a foam prefilter over the paper element and it is messy.