E-10 Fuel mileage better ???

[ChuckBerry]

My understanding is that labeled pumps may contain UP TO 10% ethanol, but most use lower amounts strictly as an oxygenate to reduce emissions since MTBE was banned in CA (and as goes CA, so goes the USA).

AFAIK ethanol has a solvent effect but not enough at oxygenate levels to cause any problems. I would suspect that people experiencing poorer gas mileage with ethanol added gasoline have other unreported issues with their vehicles.

 

[LS2JSTS]

Originally Posted By: oilmaven
My Impala is a "Flex Fuel" model and can run the E85 fuel. I've never tried it as there aren't any local stations that sell the stuff. From what I'm told, it'll run fine but have noticeably less power and take a big hit on mileage. The extrapolated savings for the lower cost of the fuel doesn't seem like it would make up for the lower mileage. The ethanol rage seems to have quieted down somewhat for many reasons.


Don't know if it's true for all Flex Fuel engines, but my 2.2 ecotec is rated higher HP and TQ with E85 vs E10. So I think they are half right, you should feel very slightly more HP, but you'll burn more fuel to get that added HP.

For anybody doing a real calculation of the differences, it's important to run a steady mix of one type of fuel. Switching back and forth screws with the curve and you'll never get your best mileage with either E10 or E85. As I said in another thread, I see about a 12% hit for using E85 vs E10. But the hit is worse at the first fill up, and improves if I keep running E85. Same with E10, when I first switch back, I dont see much of an improvement. But after running a full tank through, the mileage goes back up on that second tankfull of E10.

I think any numbers derived from switching back and forth over any short period of time and/or trip are largely useless. A real comparison would require hundreds of miles accumulated with each gas in turn.

 

[severach]

My understanding is that they can't use more than 10% or the pumps would need to be labeled or fines would be levied. They don't want to use less because that would be throwing away free money. All the tests I've done in Michigan show that E10 is as close to 10% as my small test tube can measure.

E85 vehicles are equipped with an ethanol sensor. I would think that E85 long term fuel trim would be computed separately from E10 LTFT. The only odd times for switchover is that unless you run the tank to empty you'd be running E-random for a tank or two.

The few studies I've seen that have used only new cars where the likelyhood of unreported issues is very low consistently show 3-4% loss. The trouble is that Ethanol is not necessary in new cars to keep the air clean. It's the high mileage engines that need E10 to keep the air clean and those are the ones that are reporting more than 10% loss of economy way too often.