So I was looking at my new/used 01 XC70, I'll cross post on the V and XC forum as it's pretty similar...
My 3.5yr old Son is a genetic mini-me so he always wants to "look under the hood", and yesterday he asked, so why the hell not?

While doing so I said, "You know....you should check the air filter on this thing..."

And? It was FILTHY. I ONLY banged it out on the outside workbench, and I can't believe how much crap came out. Just doing that alone my average MPGs for the same section of road jumped from 19-21 to about a solid 24 mpg leading me to believe that this thing was NOT breathing right at all.

Go figure. I wonder what will happen when I actually put a NEW filter in later today? Makes me wonder about the possibilities about an aftermarket air intake kit, Injen, K&N, etc... I did one years ago on my now ex-wife's Toyota and it brought it up to Prius type MPGs, made it noisey as hell even w/out the exhaust most kids these days would bolt on, but if it get's me more dollars at the pump I'd consider it....

Anywho... REPLACE THAT AIR FILTER GUYS AND GALS!!! holy moly.