Fuel Type - Ethanol's effect on MPG

Nope. According to their website, they are still using E0.

 

If a 10% addition of ethanol caused a 10% drop in fuel economy I'd say there was something flawed with the process, LOL.

I hope it isn't true, would speculate the drop is 2~3% at most, or there'd be a revolt.

 

Wikipedia says 2%.

There might be a little wiggle room across the country, depending whether the E10 is using the exact same gasoline for the other 90% of fuel volume as the E0. So called 'reformulated' and winter/summer fuels vary in their heat content a little.

Starting from base gasoline (petrol), etoh has 2/3rds the heat content by volume. So base petrol diluted into E10 would have 29/30 the heat content of the stock fuel.

 

Probably, but don't forget when we add 10% ethanol to gasoline, the way the gasoline is made may have to have been changed to allow for blending in the ethanol and also to make the gaso burn cleaner (EPA regs). Sort of two questions: what is the impact of ethanol per se and what would MPG be on E0 if the base gasoline were somehow optimized for MPG. Conceivably, this accounts for why some people see >3% MPG increase, if they are using an E0 with more energy content than the gaso portion of E10 they are comparing to.

It would be interesting if Toyota added a weight and volume measurement to the gaso flow measurement, then we could realize if were getting more or less energy density on fill-ups, which would give us something better to work with. Or if the gaso tank gave us a weight in the tank, that would work.

 

The prius is designed to do fine with E10 on its seals. You only need to worry about seals and E10 on cars that are 17+ years old, and if there was going to be a problem you would have seen it by now.

Ethanol is added by volume not weight, so E10 has approximately 97% the energy of E0 (pure unleaded gasoline). The actually number depends on summer/winter blends with summer having more energy than winter in most of the country.

 

Ethanol will still eat away at the newer gaskets... just not as quickly as the older ones.

 

The material in car engine gaskets in the last 20 years can stand up well to the water and ethanol in E85, E10 isn't going to hurt them. You may be thinking law mower or leaf blower engines that may be hurt by e10

 

I wouldn't guarantee as far back as 20 years...

 

Not a problem around here -- we only count as far back as 2001, the first year Prius left Japan

 

You could be right, I don't know the exact year each manufacturer made the change. All the major ones like toyota were already selling into brazil and understood the corrosive properties well. By 2001, the EPA claims (although the manufacturers dispute) that the engines and fuel systems were good enough for E15, the manufacturers claim they are fine with E10, while disagreeing with E15. That is at least 12 years

 

I went through gaskets on my 2001 Saturn because of the E10 fuel. Nothing like my '66 chevelle did before I changed the entire set, but still faster than most newer cars do. I'm sure there was a slower transition.

But can you vouch that every car ever made in 2001 was as good.

 

I can only say that every car was designed for it, with ethanol safe materials. That does not mean the ice itself was well designed. My 1998 Lexus was quite happy to run on E10 My mom's 1983 toyota corrola blew a gassket at 7 years old with E0.

 

About as much as I can vouch for cars built this year.

 

This is true, but I do know that I had to replace them twice as fast once my country gas station went to E10 than when I had E0. May have been coincidence... but those are rare.

So, you can only guarantee the one car then.

 

I need to look at those fuel specs...maybe the fuel itself is relatively good MPG fuel, so switching to E10 Reformulated gasoline might be noticeable MPG hit (I think I have the fuel details in a CARB powerpoint...posted them a while back).

When I say might be noticeable, I mean it because it seems clear MPG not too dependent on fuel make-up.

 

No

 

E-0 seemed to give better response to throttle in my '04 Prius. The mileage was slightly better at 2 to 4 mpg per tank. I would have needed to see 4 mpg plus to get to the 10% range (it did it once, not enough to say it made a BIG difference). I have just put a tankload of Philips 66 premium, to see if it makes any difference in mileage. I have been using 5w30 synthetic oil since 15k miles. I do not find any big difference in tire pressure. I drove all winter with 44 front and 42 rear. The car rode like a rock, stiff and bouncy. I went back to 37 front and 35 rear to regain some of the more comfortable ride. After all, if the car rides bad, then you will not want to drive it.

 

Presumably the Philips 66 premium is E10? What I have been doing is getting a 1.5-gal sample (in a gaso safety container) on some fill-ups to get weight/density. I am seeing about 3% higher E10 density (0.72 to 0.74 grams/cc) as the summer gasoline seems to be coming in the pumps for some weeks now. So that could be ~3% more energy just due to the shift to summer gasoline. I am in RFG (reformulated gasoline) area, so according to Chevron, I should not expect to see higher energy in premium. However, if you are not in RFG area, your premium may be higher energy, but then ethanol is about 3% debit. I hope to check premium density outside my RFG region later this summer.

 

Incorrect that high test gas has less combustion energy than regular. The recipe for regular 87 octane gas uses less higher combustion components than high test simply to get higher octane once tetra-ethyl lead was banned. Thats not to say thats guaranteed. The recipes for gas grades changes with the crude intake and it is possible but not probable. And the presence of ethanol guarantees less mpg, typically 2 to 4 mpg.
Determinig energy is done by heats of combustuion, not by density. Ethanol has a heat of combustion of about 13,000 bTu per pound while gasoline typically around 18,000 to 19,000 bTU per pound. If you had 10% ethanol your average heatr of combustion is lowered from 18.5 to 17.95 bTu per pound. That 3% loss in combustion energy automatically means you will get 2 or 3 less mpg and can be moreif the recipe is based on low grade crude to the refinery. The biggest problem with ethanol is not the loss of energy but the corrosion from water/ethanol mix; most older cars don't have good chemical resistance in their fuel systems and newer cars are much better but not immune.
One other item: when gass pumps say UP to 10% ethanol thats precisely what it means. Very little regfular gas has 10% but may vary from zerio to 10% and is more likely about 6-7%.

 

I don't have enough miles on my Prius to need it, but Seafoam did a nice job on my 2002 Camry with 185K miles. 1/3 of the can into the gas tank with 9 gallons of gas, 1/3 into the injector system, and 1/3 into the oil 100 miles before a change. Did that every 40K or so.