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This is a question for the more technically inclined (engineers and the like perhaps) regarding ethanol content in US gasoline. Due to the ridiculous EPA mandates all fuel in my Sunshine state contains up to 10% ethanol. I belive the R8 manual says that up to 10% ethanol is permitted for use but I suspect that in addition to reducing fuel economy there are other disadvantages including reduced performance. Can anyone speak to this issue? Are there any higher grade fuels that are available other than racing fuels?
 

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I'm definitely no engineer, but I'll toss in my 2 cents worth anyway. I'm currently driving a Volvo V70R which is a pretty highly turbo-boosted, octane sensitive engine (300hp from 2.5 liters). With these highly boosted turbo engines with computerized engine management, you don't hear any pinging, you just experience reduced performance if octane levels aren't adequate.

Out here in the Western US we can't ever find higher than 92 octane (RON+MON/2) and, in areas that have to meet Califronia air stds., 91 is the best you can get. (for your Europeans, our 92 is about equal to your 95 or 96, I've been told.) Volvo R's are a little challenged with those kind of octane levels and if you can get higher octane fuel, it definitely improves your performance...as has been frequently documented on various web forums by people reporting quarter mile times, etc.

So, anyway my point is, since we've been mandated 10% ethanol, most of us R drivers feel like our cars perform a little better. I have wondered if they have just added the EtOH to fuel that was already 92 octane, or used a lower octane fuel to begin with. But it is well know and acknowledged that ethanol (and also water, some of which you get with the ethanol) are knock/ping retardants, and therefore octane raisers.

So, although the specific energy content of the fuel is lower if it's 10% ethanol, thus causing significantly lower miles per gallon (mine are down 2.0 to 2.5 mpg), IF you're driving a turbo boosted engine, your performance likely will be a little better (at the expense of mileage). In an atmospheric breather like the R8, the improvement in octane is probably not worth the loss of energy, but the actual performance difference is probably nearly undetectable, I should think.

The really big problem with ethanol in gasoline is the water it brings with it and that it further attracts as it sits in your gas tank. My Yamaha engined riding lawn mower had to have it's carburetor replaced recently due to it's float rusting and breaking off!

Oregon recently passed a law allowing non-ethanol gasoline to be sold for boats, airplanes and off-road equipment, but it appears few wholesalers of gasoline are going to be able/willing to obtain such a fuel to sell, the EtOH having been added in large bulk in the regional distribution process. So we're probably stuck with this ethanol boondoggle!
 

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I received my car in March and have tracked it for a total of 10 days. Twice, after 3000 and then 6000 miles, I had an engine light. The computer diagnosis was the engine was running slighly lean. It appears that the injectors were getting clogged (slighly) leading to this warning light. The car still ran fine and I was unable to notice any performace difference. Audi says it is due to the ethanol content and the lack of lubrication the blends now provide. The solution on Audi's end is to run a cleaner directly through the injectors. I am looking for a longer term solution.

On another note, finally got my breaks working perfectly and at Watkins Glen no less. Pagid Yellow wih Motul RBF 600 was the final solution.
 

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It appears that the injectors were getting clogged (slighly) leading to this warning light.
What brand of gas are you using?

My R8 owner's manual said to use only the gas brands listed on toptiergas.com, as others have reduced detergent levels that are not up to the task of keeping the tiny direct injection nozzles from clogging.

I was surprised that a couple of discount brands were on the list, and several of the "premium" brands were not.
 
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