Eli McCraig

Can I put e85 in my my 2015 A5? And why would I?

uberwgn

Eli, the window sticker for the vehicle will tell you if it's "flex fuel" rated. It probably is.

Reggie

E85 is an abbreviation for an ethanol fuel blend of 85% denatured ethanol fuel and 15% gasoline or other hydrocarbon by volume
You can but most cars can not take high ethanol content in the fuel system and the materials used will start to corrode or disintegrate.

Google can be your friend.

Eli McCraig

Does it increase power? I've read it's like running 100 octane race fuel...

Reggie

If it was so good don't you think that Audi would be using it

ChipB

Don't confuse octane rating with power. Octane is a measure of how much compression the fuel can take before it detonates. If your engine is tuned to use high octane fuel, then it can delay ignition until later in the power cycle, which can indeed increase power. But if your engine is tuned for, say, 91 octane, and you put a higher octane fuel in, the engine won't take advantage of the higher octane by delaying ignition timing. The result is that putting 100 octane fuel in a car tuned for 91 octane will result in a car running as if you had put 91 octane in.

In fact ethanol has less energy content per gallon than gasoline; hence to achieve the same power output you must burn more fuel. That's why the MPG rating for a car running E85 is much lower than if that same car runs pure gasoline. So your car burns more fuel, which costs you money.

Bottom line is avoid E85. Running E10 is OK, and in many states can't be avoided.

socalfun64

The 2013 2.0T in my A4 was rated for E85. The eECU auto compensated for it and the power increase was awesome. The internals were modded by Audi for strength and durability. Cons are the fuel mileage decreases by like 40% though.

Reggie

Thanks for posting this. I never knew that the 4 banger was rated for E85. I looked it up and was wondering how I missed it

uberwgn

I think the 2.0T is the only engine in the USA rated for the ethanol fuel. That may have started with model year 2013.


Yeah, the EPA fuel economy ratings take a huge hit when on E85. OTOH, it used to be somewhat cheaper than Premium unleaded. Maybe not the case today??

uberwgn

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