My 2007 G35 has 40k miles on it. I drive 40 miles round trip to work. I've been getting an average of 20 mpg with conservative driving, which is pretty good for heavy traffic in L.A.

However, the last 5 tanks I've been getting only 17 mpg. No difference in my driving route or style. Tires are properly inflated. Air filters are clean. Not using the a/c or having windows open. Using the same brand gas and had higher mpg when the companies switched to winter formula in Dec.

Anything I can check or do? I'm stumped.

Thanks,
Bruce

 

Possibly your gas source has added more Ethanol to the mix? I know if I use gas w/ "10% Ethanol" on the pump I'll get at leat 10% worse mileage. I'd look for a station tha's not adding Ethanol and see how it works out.

 

Dirty Fuel injectors maybe. Probably a fuel quality issue though as blnewt stated.

 

Didn't know Ethanol had that big of an effect. Thanks

 

Between 17 and 20 is not that dramatic a change. I get similar calculated numbers unless I drive like a maniac. Mine took a dip too during the recent rains but has since gone back up.

See how it does during the current warm weather, then post again.

 

I've seen a similar drop as the OP and seems to be linked to the 10% ethanol they added in NY here recently..... Bing needs to add a feature to look for non-ethanol stations like they have to search for prices, lol.... I think it'd be fruitless here anyway.... I think all of 'em got it up here....

 

I live in LA too but didn't notice in lower MPG... If anything mine is going up slowly... Checked this morning and it was at 22.5... 95% freeway driving...

 

Up here in Canada in Ontario as far as I know, all gas has 10% to 5% ethanal except premium gas which has 0%.

we have Regular grade, Mid grade and Premium.....I believe the octane is 88, 87, and 91.

and the price difference is significant. but don't are cars require premium gas?

someone on here posted the difference in price between premium and regular gas per fill up is a lunch out, and ****ter gas mileage

so do yourself a favour and put in the good stuff.

 

Don't everyone use premium? Our car tells you to.. shrug....

 

I use premium, it has 10% ethanol in it here.

 

The premium here (in NewMexico) may or may not have Ethanol. Sams club and Shell don't use Ethanol but most others do from late Ocotober through April I believe (and it SUCKS)

 

Where in NM r u at? I went to NM Tech for a few years. I loved it out there.....

 

Roswell, but I don't have green skin, LOL.
NM Tech is in Socorro isn't it?

 

Here in the NY area, they've been using ethanol blends for years.....more in winter. That's why they refer to it as Winter Blends... I'm jealoous that folks in LA still using A/C - my MPG in winter with shor runs to the and from the train station 3-4 miles trips, the car barely warms up, 11.5 MPGs