hydraslav

Hi all

I own a 2010 Honda Civic, Manual transmission. I've been tracking the fuel efficiency with an app on my phone since i bought the car.

In the beginning, the fuel efficiency was great (better than my previous Civic that i leased). It averaged at 35MPG (6.8L/100km).
Shortly before the winter, it started turning consistently worse. In a matter of a month, it reached average of 26MPG (8.8L/100km).

I did my maintenance every time the light came up, even did it at the dealer. I even tried those fuel injector cleaners when i first noticed the issue. Then i changed the petrol station that i filled up at. No help. I then decided it was the cold winter and winter gas that was to blame.

But now, the weather is warm, and the "winter gas" stickers are gone from petrol stations, but it didn't improve...

What could be the issue? Unfortunately i know nothing about tuning up the car. So i guess my real question is: if i take it to my dealer and explain the problem, could they fix it? Or will they charge me tons of money to perform an "inspection" that will say "sorry, we don't see anything wrong"?

Thank you for the replies

sdaidoji

iTrader: (1)

https://www.civicforums.com/forums/1...6-lx-help.html
https://www.civicforums.com/forums/1...-loss-mpg.html
https://www.civicforums.com/forums/1...blem-help.html

among others

sdaidoji

iTrader: (1)

some others
https://www.civicforums.com/forums/1...-mpg-help.html
https://www.civicforums.com/forums/1...s-mileage.html
https://www.civicforums.com/forums/1...e-problem.html
https://www.civicforums.com/forums/1...o-you-use.html
https://www.civicforums.com/forums/1...ng-issues.html

sdaidoji

iTrader: (1)

some more
https://www.civicforums.com/forums/1...s-mileage.html
https://www.civicforums.com/forums/1...s-mileage.html
there are more pages, but will stop now, that should cover most of the cases anyway.

MelJ

Winter gas is more volatile than summer gas. Also, your car idles higher when you start it in the colder months. On top of that, you're running more accessories such as lights, heater, defroster. All these things start to reduce your gas mileage in the winter. Read up on winter gas to get all the facts on it. Once they switch back over to summer gas, you'll notice it go back up. Nothing is wrong with your car. And yes I'm aware that you said they switched back, but they probably just put that sign up now that the weather is getting warmer and actually haven't done the full switchover yet.

TreeFortRichard

Yeah, It depends on how busy the station is...they can still have winter gas for a little while...

HAAAAATE winter gas...It's useless..You use 30% more gas to prevent pollution?

MelJ

It's what they add to the gas so it ensures reliable starts in colder months amongst other things.

BlueEM2

iTrader: (1)

Has your driving style changed? Places that you drive to? etc. 26mpg is pretty average if your doing mostly city driving. I mean, it's a bit low, but not something is wrong low.

TreeFortRichard

Yeah, But with modern engines there is not really the effect you use to have on cold starting...It's really mostly about the vapor pressure now and winter gas boiling out of your tank in summer heat...Ethanol is another insane additive...10% ethanol and you lose 3mpg...or 10% so you use 10% more gas to got the same distance for a net loss for everyone except the oil companies and the gas taxes...Remember the govt NEEDS you to use more gas as they are losing money off the gas taxes every time you drive with better fuel economy...

gearbox

iTrader: (95)

our cars would run so much better on pure gas without additives they put in, esp ethanol. i remember a long time ago finding a station like this in a small town in the midwest and it felt like i had a new car. so much power and the gas mileage was amazing compared to what i got on the last three tanks. these additives and oxygenated crap was from over 20 yrs ago when cars didnt have emissions systems. cars made in the early 90s and after all had 3-way cat converters and produced very little emissions. most cars produced today are nearly zero emission once the car is warmed up. there are so many measures built in to help the engine and cat warm up fast that this additive business is no longer needed. i think they kept it because its an excellent excuse to make cars use more gas. and it seems this is now a year-round tradition because most gas stations i see still have the signs up that were there in winter like "oxygenated" and contains upto 10% ethanol (which is corrosive to modern fuel systems too). also with most post 2000 cars having evap systems, gas evaporation is practically nonexistant.

hydraslav

Thanks guys, just what i needed to hear. I will wait a bit more till the normal gas comes and will see if that improves.

To answer previous question: no, my driving didn't change, same route to work, about 50% on highway, 50% city (percentage is in distance)

TreeFortRichard

Hey, just had a thought...are you sure you filled your tank? If the gas shut off while filling and you didn't fill it all the way and still reset your trip odometer you would have a poor MPG on the assumption that you had a full tank...Just a possibility...

MelJ

Once the pump stops, you shouldn't keep trying to put more gas in. In some places it's illegal to do that. You're letting gas back out and into the environment.