havacgar

Anyone tried running on E85, apparently E85 has an octane rating ranging from 96 to 105 and produces a 5% horsepower gain.

Respectfully
Skeptical....

TRauppius

I would expect the octance rating to increase with the alcohol percentage as alcohol is less prone to shock/pressure detonation compared to gasoline. But, and this is a biggy, alcohol has a lower specific energy per unit volume than gasoline or diesel fuel. Thus a gallon of E85 would be expected to produce produce less mileage and less total miles covered per the limited volume of the fuel tank (i.e. MPG is significantly lower). Most folks probably have already noticed that winter gasoline formulations with up to 10% alocohol yield less power and mileage than straight gasoline with volatile oxygen boosters. If E85 is way cheaper than gas in your area you could come out ahead, but for most E85 is poor value propostion. E85 use should yield lower carbon monoxide (CO) emissions as the alcohol contains more oxygen. Also, while the ECU can handle this fuel it is actually not optimized for this fuel, and so power gains from hyper-advanced ignition settings are problematic and unlikely.

C300Sport

Anyone know why MB decided to make only the automatics capable of running E85?

RLE

Because they need to be seen as ecologically "responsible" and this is the cheapest admission ticket until their hybrids and fuel cell models hit the streets.

If E85 were available anywhere near me I would try a tank or two just as an experiment and nothing more. It will make a slow-ish car even slower.

jstaneff

This was the subject of a similar topic many months ago. At the time I ran an analysis that showed given the then current prices of gasoline and E85, that burning E85 would save on the order of 2-3 pennies per tank, adjusted for equivalent miles driven.

Given that there are potential problems with E85 in the fuel line, gas-line freeze, and etc., it doesn't make much sense to burn it.

As to that famous 10% ethanol in our Winter gasoline, I have found over several years that it seems to "evaporate" from my tank after the first few days. By that I mean that if I burn the tank quickly, the mileage seems normal, but if I take a week or so, then the mileage drops quite a bit. I don't like the stuff, but it's all we can get these days.

RLE

This theory is counter to real life. Back about 10 years ago when E10 was EPA mandated in "winter" gasoline here in certain Washington zip codes, the first tank of it produced an immediate 10% drop in mileage. That is, 20mpg became 18mpg. And in Spring when ethanol went away, 20mpg again.

Right now, ethanol is not required in Washington gasoline although ARCO has been using it all year because they make more money doing so. I use Chevron which contains no ethanol.

As to evaporation of anything in the tank, this is not possible since it is sealed.

jstaneff

Funny. I'm tanking up with Shell, and it's clearly marked at 10% ethanol. I've also used Chevron, and I normally get better mileage with Shell (by 1-3 mpg).

I've monitored my mileage for over 30 years. I've seen this winter-time drop consistently. As you know, it's rare that we have snow and ice in winter, so the difference in winter-time mileage is due to other factors. The C may use it's brakes to compensate for wet roads (i.e., drying the discs), but my other cars do not. All suffer somewhat when ethanol is in the mix.

I'm waiting for the impending rains to wash away the snow so I can go back to driving the C. What I'm actually waiting for is to see how much of my full tank remains. Meanwhile, I'm driving the Wrangler in deep snow and the XC70 on better roads.

As to the system being sealed, you may be right. An alternate explanation has been proposed by a friend who suggested that I'm seeing less BTU, thus power in the 10% mix. That's possible, but it doesn't explain the visible drop on the gas gauge.

Oh well, it's only money!

thanks

beachC230K

Probably because approx. 95++% of MBs are sold w/ automatics. no sense in spending $$$ to certify manuals on E85.

I think E85 is a "window dressing" B.S. fix to appease an uninformed public concerned with being "green".

C300Sport

Not sure what the government makes the automakers go through to "certify" E85 engines/transmissions, but the real work has alreay been done (fuel system components that can withstand the corrosive effects of E85). Seems like it should have been easy to "certify" regardless of transmission so I was curious if it was a performance issue vs. paperwork issue??

RLE

I think if you read the Ethanol label again, you will find it reads "MAY CONTAIN up to 10% ethanol."

I was in error when I posted "Right now, ethanol is not required in Washington gasoline...".

Last January, the Governor signed a bill requiring that all gasoline in Washington State contain, by December 1, "at least 2% ethanol." And this is an average number of all gasoline sold from all companies, not in every gallon. And, the gasoline companies do not reveal to each other what their percentage may be. So at this time, Shell gasolines contain 2% ethanol except their premiums which contain zero ethanol. Arco gas, all grades, contains 10% ethanol which contributes to the 2% average number which by the way is not being tracked by the state but only by a King County department for some unknown reason which is trying to keep track of who's doing what to see if the 2% average is being reached.

Keeping in mind that 10% is a level that most cars can use including all W204s except that the C300 automatic which is heavily modified for up to 85% which is E85.

I have been told by the owner of the card-op station that I use (Laurelhurst Oil) that his gas (Chevron) contains no ethanol. I will have to ask again now that 12/1 has passed.