nantucketsleigh

Over the past 2 months all of my local gas stations switched to ethanol blend. It is supposed to be a max of 10% ethanol. But I have noticed a significant decrease in my mileage. I frequently make a 186 mile round trip drive in my GL 450. Virtually all highway at 70-85 mph. Over the course of dozens of trips, my usual fill after the trip had been 10 to 10.5 gallons. The last few trips with ethanol blend have consumed 11 to 12 gallons. It does not seem possible that 10% ethanol could have such an adverse effect on mileage.

dgiturbo

Possible. My friends with E85 cars don't use it as it burns or evaporates very quickly. It's cheaper, but they fill up a lot more. In Illinois, all we can get is 10%, so there is no comparison for us.

dunderhi

I can't seem to find anything but 10% blend, but my mileage at those speeds hovers around 18.5-19mpg. With lower highway speeds I get about 20mpg. I would try another station to see if it makes a difference.

lkchris

10% ethanol in gasoline is FEDERALLY mandated. No requirement for notice at the pump. You very likely can't find anything else.

skymarc

You should be making less mileage as there is less energy in Ethanol.
Same here the only gas with no ethanol is Shell red gold.

,marc

blittle

A recent study that I read stated that most will see a 5% decrease in mileage with the use of 10% ethanol

Musikmann

Not true Kent, West Virginia has a state law that requires pumps dispensing ethanol to have a sticker. Some here do, and others do not. If I am wrong, please post a link to the federal mandate.

lkchris

No problem with that--pretty sure Feds don't prevent posting it. Just don't require it.

thebishman

Pumps here in Kansas also don't have any federal stickers on them unless they in fact do contain 10% ethanol.

I believe that the actual requirement for 10% ethanol is only in certain areas of the country that are prone to pollution. It is not a nationwide federal mandate.

Bish

lkchris

It is indeed a nationwide Federal mandate having nothing to do with pollution and everything to do with pork for farmers.

nantucketsleigh

I may be missing something but if ethanol had no value as a fuel at all the maximum impact on would be a mileage reduction of 10%. If ethanol had only half the energy of gasoline the impact might be 5%. Most of what I have read indicated that ethanol has about 90% of the energy of gasoline which led me to believe the mileage reduction would be on the order of 1% - essentially negligible. Reductions of 5% or more in mileage which many seem to be experiencing seems impossible. I wonder what's up?

StevethePilot

Not that I know anything about it ('cause I don't) but is it possible that having 90% of the energy and using 90% of the energy are two completely different issues?

STP

robalo220

From what I understand, the ethanol blend is supposed to be cleaner burning to help ease smog. However, since it does indeed have less energy and cause you to burn more fuel overall, aren't we still polluting more than if we used straight gas and burned less of it????
Sounds like the politicians are getting kick backs to push the ethanol.
Thats why I like the diesel although I pay more per gallon than gas and more in taxes! I don't think they can screw too much more with the diesel (ULSD the latest change).
If you drive infrequently with ethanol, the fuel breaks down fairly fast and the ethanol tends to attract water. Can be a problem with filter clogs and possibly frozen fuel lines in the winter months. If you drive enough to fill once every week or two, it shouldn't be a problem.
Many older vehicles have had some serious problems with gaskets, seals, etc, breaking down in the presence of the ethanol and have done some serious carb and filter clogs. Everything from farm equipment to boats.
I seriously see no advantage to the ethanol blend.

dmfick

If you have a private tank, you can get tehnon-blended stuff pretty much anywhere. I have diesel and gasoline tanks and private pumps at our farm and home, and get pure non-ethanol gasoline. That is necessary because the fuel sits for several months at a time and would separate. A big problem with ethanol is that is is water-soluable and destroys marine and farm equipment gas tanks made of fiberglass and some plastics. So most distributors do have the pure stuff and will deliver it (taxed so it can be use on road). We go out of our way to avoid ethanol blends, even in our Priuses.

mbslk350

Ethanol returns about 65% of the fuel economy of gasoline. Since the E10 blend is 90% gas and 10% ethanol, the resulting fuel economy is 96.5% of straight gas.
(.90 x 1) + (.10 x .65) = .965

So if you get 20 mpg with gas, then you should get (20 x .965) = 19.3 mpg with a 10% ethanol blend.


To continue with the arithmetic, E85 will return 70.25% of the fuel economy of gasoline.
(.15 x 1) +(.85 x .65) = .7025

So, if a car accepts E85 (most MBs don't) then you would have to find it priced less than 70% of the price of straight gasoline to make it worth buying. And you would have to not mind filling the tank more often.


I think I'll stick with the diesel-powered engines.

nantucketsleigh

[QUOTE=mbslk350;3045175]Ethanol returns about 65% of the fuel economy of gasoline. Since the E10 blend is 90% gas and 10% ethanol, the resulting fuel economy is 96.5% of straight gas.
(.90 x 1) + (.10 x .65) = .965

I have experienced about a 10% reduction in mileage. My results appear to be similar to several friends and neighbors. Letters to the editor of the local paper also indicate my experience is common and far worse than the 3.5% mileage eduction indicated by the math.

As noted above there are problems with the ethanol blend related to marine engines and to vehicles and equipment which are not used regularly in which the same fuel can be in the tank for weeks or months.

To paraphrase Mel Brooks - it's good to be a corn producer - or a lobbyist.

mbslk350

I guess there's theory and then there's real life. We've had E10 blend for years (maybe decades?) here in the corn belt so I don't have any basis for comparison.

Kaumajet

Nail, meet Head.

robalo220

I also have heard the life of ethanol blended gas is 90 days before breakdown starts occuring. And the clock starts at time of mixture. Not from when you put it into your tank. So depending on how far you are from the refinery would also effect the usable life.
The math is theoretical on the effect of reduction of economy. However as one poster said above, the high tech computers sense the change in gas and change everything from timing to amount of fuel is injected to get the proper combustion. In reality, that could be anything as noted by most posters noticing about a 10 % reduction in economy.
My wife had a 2007 C 230 sport sedan that was set up for using E-85. We never put that stuff into the car. (traded it for 2008 E350 which is NOT set up for E-85)