My 07 Prius was getting 45-49mpg until we started to have ethanol added in the gas. I tracked mileage over 15 months to obtain that average. Some tanks were lower for no reason I could determine. During the past few months mileage has dropped to 40-42. Went to the dealer and they said ethanol in the gas is the problem. The levels of this additive have increased significantly I am told over the past 4 months in the rural area I travel in. The metro area has had higher levels of ethanol for several years. I sometimes get gas there and that could be the reason for the difference in mileage I noted over the 15 months. This experience makes me an ethanol antagonist. I doubt the wisdom of ethanol as we will use significantly more fuel to travel the same distances. Furthermore I have read the studies that claim producing ethanol from corn is actually energy efficient. I simply deny that claim. How can corn grown with fossil fuel fertilizer, cultivated with diesel burning tractors and then processed in plants with more energy be energy efficient.
you most likely have E10 which is 10% ethanol. now ethanol has about 10% less power than gasoline, so its only going to equate to around 1-2% drop in gas mileage. in Western WA, E-10 has been used forever here. check my stats... trust me, your mileage is not because of the gas mix...(assuming its mixed correctly that is) so look at other things. my Dad lives in Texas a few miles from Mexico and a short shot from the Carribean. they dont have any ethanol there and he only gets about 40-42 mpg in his 2007. but he doesnt drive much... lots of very short trips, stop and go, etc... A/C nearly all the time, etc...
This was the substance of the debate that occurred before the policy decision was made to emphasize ethanol as part of an energy independence strategy. It didn't hurt matters any that some of the largest agribusiness interests (companies like ADM) were pushing for ethanol.... dubya will never be accused of not taking care of the corporate interests that got him into office. Don't you just love it when the fix is in?
Same here in Minnesota. Winter has a profound effect, from a variety of different factors. Right now, it's the humidity. The endless mist has actually pushed efficiency all the way up to 52 MPG. The normal bone dry conditions contribute to the opposite, dropping MPG into the low 40's.
If you have been tracking milage over the past few months I am going to assume your local temperature has dropped as well? You accounted for such things as temp. and road conditions right?
We tracked mileage over one year, through last winter when we had similar conditions. If we had experienced a drop in efficiency at random times throughout that period, I would say it is due to driving habits, etc. Higher ethanol levels have been mandated for the county we live in over the past 3 months. That is roughly the same period we have noticed the drop in mileage. However I will follow up with the dealership as they did change the oil the last two times. Other than the incorrect viscosity of the oil, is there any other things a mechanic can do in the routine oils change that will foul up fuel efficiency?
There is a more fundamental problem, the energy content per unit of fuel regardless of the what it is mixed in the batch. There can be a significant, measurable difference in the energy content of the fuel but there is nothing posted allowing a consumer to make an informed choice. Bob Wilson
MBTE (the carcinogenic oxygenator that was used before EtOH) also had lower energy content than gasoline. That's a uniform characteristic of the oxygenators.
MBTE may not have been as bad a trade off as far as energy is concerned, but other issues makes be glad that ethanol is used.
I have continued to informally research this subject by visiting with friends who do track mpg. They drive all makes and models, not just energy efficient hybrids. So far of 14 people I have visited with, all have noticed a drop in mpg from 8 to 15 % when using E10. A few have friends in warmer climes (Hawaii, Texas) and they even report a 10-15% decrease in fuel efficiency. Perhaps this is not just a winter time problem.
Yep, that's why mass distribution of E85 will probably never happen. Once people realize that E85 yields about 40% less gas mileage for about the same price/gallon as gasoline, sales of E85 will drop like a rock.
Is that data introduction or several years? First using it will have a cleansing effect, since the alcohol tends to flush out and confuse the system. So that initial data can be misleading. 3 to 4% is what we (10 years of use) have observed, matching the energy difference between pure gas and E10. .
Gasoline has an energy density of ~34.6MJ/L (by volume). Ethanol is ~24MJ/L, or ~31% less than gasoline. For E10, the 10% ethanol constituent theoretically drops engine efficiency by 3%. So, for an engine that is optimized to handle ethanol, or gasoline and ethanol equally as well, a 3-4% drop is expected. Most engines are not optimized for ethanol, though, and experience a significant drop in efficiency. 8% would not be unreasonable. That's also why gasoline-oriented engines, if properly equipped, running on E85 are likely to see an efficiency drop around 40% rather than 30%. Just because an engine can run on ethanol doesn't mean it does so as efficiently as gasoline.
hmmm if that is the case, then on reg gas, i would be blowing the OLD EPA estimates out of the water...cool!
True. But keep in mind the equation isn't linear. The new studies are revealing unexpected results, like E20 causing less of a MPG hit than E10 in certain non-flex vehicles. .
