Hoi,<br><br>Has anyone here replaced their AC air filters, yet? I just replaced mine and my mileage went up from 48 to 51 mpg!<br><br>Also wondering about gas mileage improvement in using better engine air filters. K&N makes an air filter that supposedly increases performance and gas mileage. Wondering if anyone out there has experience with it.<br><br>Cheers

I would be wary of those types of air filters. The principle behind the performance improvement is that air can be pulled through the filter with less effort while still being filtered the same as standard filters, thus the engine has to do less work getting the air in to it and you get improved performance. The principle is fine, but in practice, those filters tend to do a poor job of filtering the air. This can lead to increased engine wear, and I would highly recommend against them if you are in a particularly sandy/dirty area. If you trust the air quality and the quality and cleanliness of the roads, then those filters may be suitable. IMHO I will let my engine do a little more work for cleaner air.<br><br>-Joe

You replaced your AC (air conditioning filter, in the glovebox??) and you mileage went up???? or you engine air filter? That must have been one dirty filter. More likely warmer temps in your area.<br><br>Toyota TRD sells a filter similar to the K&N filter. May even be a reboxed K&N(??) I do not know if they have one to fit the Prius though. <br>Charlie Fosdick

Hi CHAS:<br><br>Yep, K&N makes a replacement air filter for the Prius. Got one installed along with a Tornado Air fuel saver. Awesome combo for additional ICE power. FYI.<br><br>-Michael<br>CA "01 Prius"

Hi RIGBY:<br><br>With K&N installed, have only seen ICE performance increase, not fuel mileage. FYI.<br><br>-Michael<br>CA "01 Prius"

Hello: Yep, changed my air filterto a K&N air filter. My mileage too went up by 3.5 miles per gallon. My wife says the car has more "pep" when it comes to getting power to change lanes. It's an improvement over the standard paper filters. I changed the air filter for the Nissan I also own and got similar results. The Toyota dealer mechanic told me that the car was "engineered" to use standard air filters...yea right! Keep on trying to tweak the car for higher gas mileage and I'll do the same. Tires are next.... :)

It all depends on how well you keep the K&N serviced. I've run one on my Dodge Ram 4X4 (what I drive when I'm feeling evil....rootin', tootin' and pollutin') for the last 100,000 miles and I've not experienced any loss of compression or oil burning...and it's got a total of 200,000 miles on it! But, a word of caution...the K&N is a pain to clean...but less stress on landfills. I will not be installing one on my Prius and I would suggest that other Prius owners think very carefully before doing so. Also, it may freak out Toyota.