miller89

Does anybody know what could make me lose about thirty miles on my tank of gas. For the last three months I had Been getting about 280ish miles to the tank and this last tank I got about 255.... And about 2 miles less to the gallon. The only thing I've done to the car is change my oil to Amsoil 5w20.. Any body have any suggestions or ideas? And I understand if I had been driving spirited a lot that would change it as well but I havent been which is why I'm confused.

AzPete

More stop lights or catching them for a longer time, idling, running A/C harder based on outside temps, higher humidity, maybe not filling tank the same, hotter temps cause fuel to expand, miss calculations if using dash readings......so many possibilities but one tank is hard to make a real decision on.

Mishri

I agree with AZpete. 280ish is what I get after going to 4.10 gears, with non stop highway driving, cruise control at 75mph. before i got the gears I used to get over 300 miles per tank. with a lot of intown driving im at the 255 range. (lots of idling and stop and go)

BigDinTexas

Also, the quality of the gas you've been getting could have gone down or the ethanol content has gone up, or worse yet, both... Theoretically, I could see the MPG's dropping for either event.

Don

Derf00

age of fuel filter and air filter? when was the last time you replaced them?

BigDinTexas

The OP has a 2011, so the fuel filter is one of the "lifetime" filters, but the air filter might have this affect when combined with higher ethanol content... If memory serves me right, E85, while cheaper per gallon, gets around 20% fewer miles per gallon than straight gasoline...

Don

Mishri

you aren't supposed to use E85 in these cars...

oh.. as long as we are going into maintenance you can also over-inflate your tires and get a bit better mileage (and wear out your tires faster, i think higher risk of blowout as well).. so check tire inflation.

BigDinTexas

Oh, I know... In my area, all of our gas is E10 blend, which means there is maximum of 10% ethanol in each gallon... This is pretty common across the nation... Unfortunately, there aren't any all gasoline (non ethanol blends) retailers within 150 miles...

My post was trying to say that the OP may have been getting an E10 blend that only had 5% ethanol for a while and was used to that MPG based on that, but that maybe the refinery recently upped the ethanol content to the maximum allowed (10%)... I used the example of E85 to point out that ethanol has less energy compared to good 'ole gasoline and that when you increase the ethanol content up to the E85 level, the MPGs can drop 20% (sometimes as much as 30%-35% depending on source of info) when all other things/conditions are the same.

Don

Nuke

There are way too many variables. Also, using the miles per tank method is very inaccurate. It's best to hand calculate at every fill-up (and compare that to the on-board after resetting it at each fill-up) and you should have a good idea of average MPG's after a few months.

Not every tank of fuel is comparable to the previous tank so that in itself will skew your data. Add temperature changes, tire pressure changes associated with temperature changes, humidity changes, wind speed AND direction, road surface, # of traffic lights, timing of traffic lights, average speed over that tank of gas, the # of "spirited" trips, and a number of other variables will impact average fuel mileage.

miller89

Wow more responses than I was expecting. Sorry my info is wrong, I actually have 2013 gr with only 3100 miles on it. I understand there are far too many variables to count, the only reason I am concerned is the fact is has been extremely consistent in mpg's and miles per tank except for this last tank and this current one I'm on I seem to be getting less per gallon already. I understand my car's comp is not 100% accurate but it's been pretty good to me so far.