Hi All,
I feel your pain, I have a 1997 Buick Regal, a 1989 GMC Van, and 3 Motorcycles that used to drop in fuel mileage every winter here in Albuquerque. The recorded percentage drops (via spreadsheets for each vehicle) are about equal to what Doug Sage is experiencing.
It is true that the energy content of ethanol is about 25% lower (actually 35.4%) than that of gasoline per gallon, but it is my belief that since ethanol naturally has a higher octane, and since the EPA has mandated it’s use year round for every state, the producers are mixing it with less highly refined gasoline to come up with the same octane as before with regular gasoline which equates to increased profits. Well, maybe not exactly. The unseen costs of adding ethanol to the fuel probably makes it a wash. And just wait till the subsidies on ethanol run out! I hate having to buy premium just to get back to where we were but it’s the only thing my vehicles will run correctly on.
I also believe that Doug is correct that we now use more gasoline than before. This makes the argument moot that the oxygen in the ethanol will reduce the emissions. The single oxygen atom in ethanol may reduce emissions in really old cars that are tuned rich (the original reason for ethanol years ago), but in modern computer controlled, O2 sensor equipped, injected engines, I find it very hard to believe.
As to the claim that the theoretical decrease in economy, for 10% ethanol, should be around 4%. It is actually a theoretical decrease of 3.44%, but the reason the economy drops so much is that the oxygen in the fuel fakes out the O2 sensors and the computer tries to compensate by enriching the mixture at all speeds. This alone negates the reduced emission claims. The only way this can be properly compensated for is like they do on new flex fuel cars, ‘sense’ the percentage of ethanol in the fuel, and correct for it.
Even then, the mileage on E85 is reduced from the theoretical of 34.4% to the 35% or greater drop reported by N Dienes for the reason listed above in paragraph 2. Given the octane difference, you could probably mix corn flakes with the ethanol and still get 100 octane!
All info that follows is dependent on where you look and what numbers you use, but is relatively realistic.
______________Net BTU/gal (U.S.)______% decrease_____Octane
Reg. Gasoline______115,400_____________________________ 87
Ethanol____________75,700______________35.4%______ ___122
________________HHV BTU/lb__________% decrease
Gasoline___________20,400
Ethanol___________12,000_______________41.2%
I’m sure glad we aren’t paying by the pound at the pump! Ops, let the cat out of the bag. I hope the EPA doesn’t read this web site! Uhhh… lets see, now they want to raise the ethanol to 15% or 20%. Good thing I don’t believe in conspiracies! Seems like they want us all to buy ‘new’ flex fuel cars made overseas? Headline: New E85 RV’s get 5 MPG!
Interesting.
Ethanol