By turning the TCS button off, I've noticed an increase in my overall FE. I've seen an increase by at least 1mpg. The button is located to the bottom left of the steering wheel (next to the sunroof/fog light button). Why is this? I don't know... maybe the engine doesn't have to work as hard... but I have seen these results in both my older 2004 accord exl v6 and my current 2005 HAH. I have also noticed with my HAH, when I put in 91 octane gasoline, I will get another 2mpg increase. I believe the 91 octane may help with the Variable Cylinder Management (VCM) deactivation... but thats another subject. For the TCS OFF button... try pushing it off every time you start your Honda and compare the mpg with your prior tank/trip... you may notice a slight increase like I have. Let us know your results.

 

I can't believe you got any better gas mileage with the 91 octane fuel. I tried that once and my mileage actually was worst off. I've talked to others who also say the same thing. Regular gas is the only grade I'll put in my HAH. Premium will not make this car run any better, period. I have have tried fuel additives and they really don't help at all.

 

Actually running premium fuel will make a difference. See this article. Info is straight from a Honda engineer.

http://www.usatoday.com/money/autos/...1-accord_x.htm

You will gain 10 horsepower and 10 foot pounds of torque. I know I noticed a difference on my 2005 HAH. Especially in cold weather the engine runs quieter on start-up and has more pep. Make sure you do at least 3 fill-ups with premium to flush the tank of regular.

 

Well, I do know I get worst gas mileage in the winter, especially a cold winter like this year. I can't get any better than maybe 28mpg right now. Live in IL and the cold eats my gas up. Putting premium in my tank won't help it at all. You find another driver that confirms this and maybe I'll try again. But with the price of fuel here I'm not using 91 octane. Just how many miles do you have on your HAH? I have over 166K and fortunately its still hasn't had a new hybrid battery yet. Premium gas or any additives seem not to help my car at all.

 

Every car gets worse mileage in cold weather. I'm not saying premium gas gives better fuel economy. I'm just saying the engine runs better. I have 73,000 trouble free miles on my HAH. I just like the extra horsepower and torque. The way I look at it, premium gas is only about $3.40 a tank extra, so why not. Premium is only 20 cents a gallon more here in California.