Type of gas?? Ethanol question

Yes, it matters. The energy content of 10% ethanol gasoline is 110,000 BTUs, as opposed to 114,000 for pure gasoline. So, mileage will be about 3.3% lower. On the other hand, ethanol is a good alternative additive (needed in gasoline) rather than Lead or MTBE, which had bad environmental effects. Nothing Prius specific about any of it.

 

...what Corwyn said except the main reason we have ethanol additive is Congress mandated it. In some areas you can get ethanol-free gasoline. You might see a little better 1-2 MPG, but if you are paying much more it will not be cost effective. If you could get it for the same price, I would go with ethanol free. But I don't have the option.
Otherwise there is no real downside.

 

Either 87 0ctane gasoline or 87 or higher octane E10 will work fine.
IF an engines ability to convert heat (BTU's) to power was a constant, you should get slightly lower mpg with E10. ( up 3%)
The truth is that other factors of the gasoline or gasoline / ethanol blend also affect the engines ability to convert heat to power, or waste it through the exhaust or cooling system, so your mpg with a given fuel type may vary due to octane level or other factors. If the fuels octane number or other factors cause the engine to retard the ignition timing to stop fuel detonation, more BTU's of heat from a gallon of fuel will be wasted as exhaust or cooling system heat, rather than being turned to power to drive the car, giving you lower mpg.

The problem I have seen in states that MANDATE ethanol in all gasoline, is that the fuel blenders will substitute a lower cost but lower quality gasoline and use the 10% ethanol to bring the sub standard quality gasoline's octane numbers up to the legal minimum of 87. This junk will usually slightly lower your mpg.

I am lucky enough to live in a state that does not mandate ethanol in all fuel, but there is a lot of support for biofuel blends for those who want it.
A local station has blender fuel pumps that will pump ethanol free 87 octane gasoline, 90 octane E10 made from the good 87 octane gasoline with 10% ethanol added for 90 octane. it also pumps E30 and E 85.

I have experimented with the different fuel blends from this pump for 3 years in my 2010 Prius.
After years and many tanks of both pure 87 octane gasoline and 90 octane E10 made with a good quality 87 octane gasoline stock, I am very pleased to find that my Prius consistently makes around 2 mpg better with the higher octane E10 blend. Better mpg and I am burning 10% less imported oil.
The final answer is it depends.
E10 can give you slightly less mpg IF the gasoline portion (90%) is it made with a lower qualty gasoline stock, or slightly higher mpg IF it is made with a good quality 87 octane gasoline stock.


For those that still believe the old lie from big oil, that it takes more oil energy to grow the crop and make ethanol than you get back in ethanol energy, well, the latest numbers from the USDA is that the energy gain for a modern ethanol production system results in a 30% energy gain. (Plus after the crop is converted to ethanol, nearly 1/3 of it, the distillers grain, is still there as a high protien human or animal food. Using E10 in your Prius results in less imported oil and makes your Prius partly solar powered , as the 30% energy gain with ethanol is from the sunlight growing the crops to produce starch/ sugar / ethanol.

 

We would have some additive, no matter what. Ethanol appears to me (someone not conversant with fuel characteristics) to be the best option. The specific concentration (which is probably higher than needed) is an effort by Congress critters and their sponsors to increase corn usage. Given the choice, I would probably be using an ethanol mix at a lower concentration than current mixes. If we start making ethanol from a more efficient resource (perhaps algae) I would convert to a higher concentration.

 

^^^I guess there are 2 legal reasons ethanol is in gasoline. Primarily, if you live in a ozone non-attainment area, then the Fed EPA mandates reformulated gasoline with ethanol for your region. Secondarily, presumably the state could step in and mandate ethanol even if you are not forced by the Feds. Sounds like North Dakota allows an interesting variety.

 

No don't need an additive (for octane). Take the previous post by Jon Hagen he can get ethanol free in North Dakota. The oxygenate additive is needed only because Congress said in 1990, thou shalt have oxygenate additive in ozone non-attainment areas. That oxygenate became solely ethanol after the probs with MTBE surfaced.

 

At $3.50 for E10, and $3.75 for E0
500 miles /50 MPG = 10 gallons = $37.50 for E0
500/48.5 MPG (3% less fuel efficient) = 10.3 gallons = $36.08 for E10

With that surcharge, you spend less money with E10, you import less oil with E10, but you stop to fill up 3% more often.

 

Ah, I live in a perfect world. In ND, the good 90 octane E10 that gives me more mpg than the pure gas 87 octane regular, is 5 cents per gallon cheaper.

 

If the rig is a daily driver the e-10 will be cheaper to use overall. If you are the kind of driver that takes weeks or longer to use up a tank of fuel the ethanol free fuel is your best LONG TERM fuel choice. Eth fuel does not store well AT ALL. It not only breaks down MUCH quicker than regular fuel it actually draws moiture out of the air. Its a bad idea to let a half full tank of eth sit for long, it is worse the higher the humidity. As to the REAL impact on the ecology the jury is still out. The only thing that is sure is a lot of money is changing hands.