FuelEconomy.gov official ratings posted - 58 City/53 Hwy Prius Eco - 54 City / 50 Hwy for Prius

I am pretty sure EPA multiplies observed MPG x 0.97 to account for sticker MPG. Its not just the E10, I think (at least in the past) they use juicy fuel with good energy content and not aromatics depleted EPA reformulated gasoline like most of us use. Among other things, there needs to be a fuel correction factor for what we actually see at the pump. Good question what they use though. In their battery of tests I wish they'd throw an E10 test in there, so we could see impact on different vehicles.

 

they mandate ethanol and winter blend, but test with ped's?

 

We should be more careful with our wording here. The EPA don't test every vehicle. They mandate the manufacturer do that and submit the results. It's supposed to be done by an engineer, with his/her signature on the documents (meaning he/she could loose their credentials if caught "fudging" the results). Yup, that worked well.
The EPA, up to now, have then done the tests themselves on some of the vehicles, I've heard the figure of 10% thrown around.
That may all change now after the Hyundai and Volkswagen fiascos. Or not. What they are allowed to do is driven by political philosophy.

 

It is also premium octane.

There is 'talk' about changing the test blend to an E10.

No, that was Congress.

 

ah, thanks.

 

Hi guys, do you know if Gen 4 is fully (officially by toyota) compatible/working with E-85 (super-ethanol)?

 

No. It's not compatible with E85.

 

At one time in 2012, Toyota announced the Brazilian Gen-3 could run on ethanol. I've tested the Gen-3 and it works fine on E-50. But above E-50, it sets the 'Check Engine' light.

Bob Wilson

 

Thanks for the quick answer. Too bad :-(

 

It runs on E-85 but a little hard to start on cold mornings. Just put a piece of black tape over the 'Check Engine' light and the problem is solved. <GRINS>

I'm not having a lot of success with Google finding Brazilian references to the Prius. My understanding is only 400 were sold over a two year period.

Bob Wilson

 

I thought there was an E85 conversion kit some have used on Gen2/3

 

I bought one and briefly considered it until the USA retail price of E85 made it a no-go.

Bob Wilson

 

Personaly, i don't like the idea of a third party with a basic electronic that increase the time of aperture of injector. Too bad toyota didn't manage to have flexfuel on the hybrid system (superethanol). I mean you can put regular and superthanol, whatever the car work fine. Here in France we have loads of station that can give you E85. It is a lot cheaper ^^

 

OK that makes sense (as far as EU application) I believe there is a fairly nice how-post from a Germany owner...i know you are hoping for OEM solution

 

OK, the purchase price of E85 is lower. But what about the per km price? There is a lot -less- energy in E85 gasoline. I'm betting it costs the same or more to use it on a per km basis.

 

The problem with driving with the check engine light on is that the ECU will default to open loop; ignore oxygen sensor input and just follow some default fuel trim maps. The car will be running rich and wasting fuel.

On newer cars, drivability can also become annoying with the CEL on. Had it come on a couple years ago because the gas cap was loose, and the car started shifting hard.

In regards to E85 in a non-flex fuel car, I'd worry about the long term health and reliability of the plastics and rubbers used in the fuel system. Flex fuel cars are more than an alcohol sensor and E85 fuel maps in the ECU.

Depends on the engine. Some flex fuel engines can see a fuel efficiency per btu increase at 30% to 40% over gasoline. The efficiency by volume will still be lower, and most flex fuel engines can't take advantage of ethanol's higher octane.

Like trying different octanes in engines that can make use of the knock resistance, it will come down testing it out in the car.

If the car isn't flex fuel, it will dump more fuel than needed into the cylinder, and fuel economy will drop farther than what the energy content will explain.

 

What I found in my Prius test with both our 03 and 10 Prius:

• fuel efficiency followed ethanol content
• OBD observed fuel trim followed normal patterns
• USA retail price in Huntsville is not proportional to energy content
  • wholesale ethanol price follows energy content, sometimes lower

It was the retail price of E85 that ended the experiment.

Bob Wilson

 

I guess it depends of price tag for gasoline for each country. In EU, taxes are really high so you still have an economical benefit. The price tag is a lot different and it was particulary true few months ago. In my country you pay 1.5$ per liter for régular and 0.9$ per liter for E85. You have a 35-40℅ price difference. Even if you are right, you will consume more with E85, +20%, you still win. And if your car is flexfuel, you can put whatever you want

 

I wanted experiment with different ethanol concentrations in my flex fuel Ranger, but we didn't have a convenient station with E85.

Experimentation is fine, but I'd dissuade the long term use of E85 in a non-flex fuel car. Potential fuel leaks are something to avoid when possible. If the plastics and rubbers of the fuel system aren't designed for high ethanol amounts, they will slowly dissolve from it. Then the water that always comes with ethanol tends to be low pH and salty. So metal fuel parts can also corrode from the high ethanol content.

 

Due to the help from many members of this forum I have managed to download a copy of the owners manual for the 2016 Prius.
It contains the following:
"If you use gasohol in your vehicle, be sure that it has an octane rating no lower than 87.
●Toyota does not recommend the use of gasoline containing methanol.
●Use only gasoline containing up to 15% ethanol.
DO NOT use any flex-fuel or gasoline that could contain more than 15% ethanol, including from any pump labeled E30, E50, E85 (which are only some examples of fuel containing more than 15% ethanol).
DO NOT use gasoline containing more than 15% ethanol."

So there's your answer "from the horses mouth".