Hwy MPG improvement with K&N filter
 

Just changed my stock filter to a K&N and picked up a gain of 3.0 MPG on the highway (24.8 before & 27.8 after). I have not checked the difference in city mileage yet.

What condition was the stock filter in, the one you took out?
If it was dirty that would have an effect on the mileage.

The stock filter I removed looked pretty clean. I've had the car for 4 mos and the filter was changed at that time.

Put the old filter back on and see if it makes a difference the next time.

Only way to know for sure is if it's repeatable and consistent.

I'd have to agree that is the only way to explain it (or a different driving style or route).

What they're saying is K & N's have failed to show that kind of improvement in controlled testing. If they did, we'd all have one. However, the down side is they let more particles into the intake than a quality stock element. That has been shown in controlled testing.

+1
:cool:

Be careful. As far as keeping things clean. Had a bad experience with a cone style K&N on a different vehicle, the design of the cone had an inverted "V" shape at the tip with the K&N filter element. Well, that part came apart after using it for approx a year, and was fluttering around inside the cone. The car was acting funny and was too late, the MAF got dirty and cooked the platinum wire. I would probably only go with a panel drop in, but unless I read somewhere that it is definitely worth it (sound, fuel, performance), I'm sticking with the stock filter for the reason of simply keeping things clean.

There isn't any real horsepower or efficiency to be found in the aircleaner on a Carrera. The only gain is if the old filter is dirty. An airfilter doesn't need to look dirty to be clogged enough to reduce efficiency.

no improvement at highway throttle opening...there's no difference between a slightly better filter or a slightly less throttle opening...either way the same amount of air goes in the engine therefore uses the same amount of fuel....