Reduced MPG..???
 

I live in WNY - so I've been looking forward to the warmer weather and better MPG. I took off the studded snows in April. The only other thing I've done is an oil change. My tanks have not been as good as last summer. They've not even been as good as some of my winter tanks. I put on Yokohama Avid TRZ's to replace the original LRR Insignia 200. I have checked the oil, tranny fluid, air pressure. I have about 50K miles - so I shouldn't need spark plugs yet. Last summer on trips and driving slowly I could get a tank of high 50's or low 60's. This summer I've been getting high 40's and driving the same. I also put in a K & N air filter. On same trip on CC I actually lost 3 MPG after I changed the air filter. I'm getting discouraged. Any suggestions? :confused:

Re: Reduced MPG..???
 

Looks like tires make a big difference in mpg. I'm surprised about the K&N results.

The suggestions are obvious, although probably not practical -- go back to LRR tires, and go back to the factory air filter. Maybe you could leave the filter, but sell the tires as "slightly used." At least get some of your money back.

Re: Reduced MPG..???
 

Hi Don;

Sorry to hear about your mileage drop.

Cars like the HCH and Prius really need LRR tires to even begin to show their stuff and almost everyone of the thousands that have tried everything else end-up noticing significant drops in their mileage.
However, one of the things you may consider to do is up the tire pressure on the new tires a little in order make up for the greater rolling resistance. Just as an experiment, place the new tires at their maximum rated pressure (or some PSI lower than that) and try to crank out some FE segments just for giggles. You'll notice (like many others have) that you'll get most of the lost FE back.

One other thing I would do is check the alignment. As an example, I have an alignment
performed every two years and when I do I always notice a deviation from the previous readings (I get an alignment done at purchase time as well).

The K@N factor has been discussed often in high FE hybrid circles and found not to be a significant issue in any mileage drop. To the best of my recollection nobody ever claimed an FE increase either. Personally, I don't have very high regards for K@N filters outside the tuner crowd as some of the field data and the odd service related issues seem to make them a risky proposition for the average driver.

Cheers;

MSantos

Re: Reduced MPG..???
 

FWIW, I drove with a K&N filter for roughly 10k miles, and found that while there was a *subjective* increase in pick-up on one rather nasty hill+merge, it did absolutely nothing in terms of fuel efficiency. I put the factory paper filter back in just before my 30k service (which came around 27k, I think), and sent the K&N to a gent who wanted to try it out himself. Verdict? Not worth the bother.

Re: Reduced MPG..???
 

At what intervals do you guys change you air filters? I'm assuming before the 15K service mark?

Re: Reduced MPG..???
 

Hummm...

I change mine every 12,000 miles (20,000 KM). Why?

This is the engine air filter (dirty one on the right):
https://www.greenhybrid.com/share/fi..._AirFilter.jpg

And this is the cabin air filter (dirty one on the left):
https://www.greenhybrid.com/share/fi..._AirFilter.jpg

Anyhow, a close-up of the filters will reveal a disgusting world of dirt enough to convince any unbelievers that it is worth keeping an eye on these things. ;)

Cheers;

MSantos

Re: Reduced MPG..???
 

I had a 2003 civic for about 2 years before I even knew it had a cabin filter....needless to say, when I finally got around to changing them, they were horrendous! They actually managed to have dead leaves in them by that time....I did get better air flow and sneezed less once they were changed!

I changed my air filter in my 07 HCH after 8 months ~ 7500 miles. I drive through quite a bit of road construction in this area all the time and slow, creeping along traffic with the tailpipe of the car in front of me pumping who knows what into the grille of my car. I did put a K&N in my HCH though, didn't notice an FE difference, but figured that I'd give it a try. Since I own a pickup also, if it takes a little longer for the K&N to dry and be ready, I can use the pickup for a day if necessary.

Re: Reduced MPG..???
 

The first one I changed I let go until the recommended interval, and witht he new filter I noticed the improvement in performance. It made a much bigger difference than I expected.