Trying E85 for first time - '09 MB C300

[pezzy669]

Hey all!

So being I now have my first Flex Fuel (E85) capable vehicle ('09 Mercedes C300 - 3.0 RWD. C300 4Matic's are NOT flex fuel) I finally decided to give E85 a whirl. When I purchased the car the thought of using E85 never crossed my mind until the first fill-up of the required premium @ 3.09/gal in Atlanta (Fulton County) prices which was quite a sticker shock coming from 87 octane fueled vehicles. Yeah I can save ~$.20/gal by going to a neighboring county (DeKalb) but the time and distance (~4 miles each way) is not something I want to or justify doing.

On a recent work road trip to Tennessee where I was pretty much forced to take my vehicle due to overbooking by my local rental company I finally decided to give E85 a whirl once I ran out my tank of premium. Fortunately Speedway in TN stocks E85 at it seemed like all of their stations so it was not difficult to find. First fill-up from reserve tank (~30 miles remaining) was at $1.44/gallon (vs $2.27 for 93) for a whopping total of ~$25 to first click off.

First impressions

- Mileage immediately tanked as expected.

- Performance dropped off for the first 30 miles or so until the fuel trims could adjust. Highly doubt this car ever saw anything beyond E10 in its first 62k miles before I bought it. Performance has leveled out but it still does not feel as sprightly as it did on Premium, I would say 5-10% reduction in performance. I will admit I am still getting used to the car so this may all be in my head.

Road trip comparisons and calculations.

- Please note this is all based on the car generated MPG readout, all sorts of different pumps were used so hand calculations would be off just as much as the trip computer.

- Cruise control was used ~90% of the time at 10 MPH over the limit - (~70% @ 80 MPH with the occasional construction zone and speed reductions thrown in). Average readout was 64 on my way to Nashville and 66 MPH on the way back so very close when considering distance. There were 1/2 dozen or so WOT kickdown runs each way to ahem extra legal speeds to get around some fast lane rolling roadblocks.

- Premium unleaded was used on the trip from Atlanta to Nashville, TN @ 27.7 MPG final readout.

- Speedway E85 was first installed as soon as I was rolling into Nashville on reserve fuel. Burned through about 1/2 tank of that doing my circuit route of Nashville metro area for work.

- Speedway E85 was topped off to full right before my return to Atlanta. 20.4 MPG final readout, E85 had a slight disadvantage as I had to idle around a shopping center in my car for lets say a combined 15 minutes at the 1/2 way point on my return (Chattanooga)whereas the Premium had zero stops. Think this was a .4-.6 MPG penalty.

Final Results

Using excel I paid 36.5-37.8% less for E85 versus comparable premium at both pumps. At Speedway in Tennessee it was $1.44/gal for E85 vs $2.27/gal Premium. In Atlanta the price spread increased even more, at my local E85 station it was $1.89/gal for E85 vs $3.04/gal Premium.

Mileage reduction for E85 on the round trip was ~26.35%, fuel cost was ~37.20% lower. Very much a win win in this accountants handbook.

I know there are still a lot of unknowns by using E85 and this is a time where Google searching has given me wildly different opinions and answers on all aspects of using E85. The only common conclusion on E85 is it is cheaper and reduces your fuel economy. When it comes to performance, longevity, emissions, cleanliness, etc. you will hear wildly opposite opinions.

While I am venturing into the unknown I am going to continue filling up with "up to" 85% ethanol. While I understand the alternative fuel argument of Ethanol is not complete when it comes to emissions, sustainability and mechanical longevity or performance, I do feel better in knowing that 85% of my fuel is going to support our domestic farmers and ethanol refining facilities versus the unknown of where your gasoline is coming from.

Your results may vary! I think if my car took regular unleaded the results may have come out wildly different in the favor of gasoline, however with the price premium of 93 E85 is an expense reduction for my car.

Let me know your thoughts or if you have long term experience running E85 as I would like to hear it from some of the most knowledgeable car people in the world versus what you find during a Google search.

Thanks!

 

[pezzy669]

On another note this car pleasantly surprised me by handily beating EPA estimates on both fuels despite high speeds and quite a few kick down runs to triple digit speeds.

Premium - Beat EPA hwy estimate by 9.8% (27.7 vs 25 rating)
E85 - Beat EPA hwy estimates by 6.9% (20.4 vs 19 rating)

 

[Wolf359]

Are you going by the trip computer or are you actually factoring in the mileage and actual fuel used at the pump? MB's computer tends to be a little off on the high side.

E85 doesn't make sense around here because once you factor in the lower btu per gallon, the discount isn't as much. On the other hand, you're in a location where E85 is near the source and hence isn't as expensive due to transportation costs. In theory E85 is supposed to give you better performance. It's been pretty hot lately so engine performance will suffer. See what you think of performance when the air is cold and there's more oxygen.

 

[JC1]

Thanks for the info. Are you going to continue to run E85?

 

[pezzy669]

Originally Posted By: Wolf359
Are you going by the trip computer or are you actually factoring in the mileage and actual fuel used at the pump? MB's computer tends to be a little off on the high side.

E85 doesn't make sense around here because once you factor in the lower btu per gallon, the discount isn't as much. On the other hand, you're in a location where E85 is near the source and hence isn't as expensive due to transportation costs. In theory E85 is supposed to give you better performance. It's been pretty hot lately so engine performance will suffer. See what you think of performance when the air is cold and there's more oxygen.


I didn't do any hand calculations as it was a road trip and multiple different stations and pumps were used, I filled up as soon as I got back home and I have exactly 1 pump to go to at my nearest station so will be doing that going forward to see what the variance is vs hand calculation. I don't understand why trip computers can be so off as the ECU knows exactly how much fuel it is metering, guess the automakers are dumbing it down for some reason. I found in previous car with trip computers that longer trips resulted in more accurate readings whereas multiple short in town trips through a whole tank would cause a huge discrepancy. My last Jetta would have near 2 MPG discrepancies when I burned through an entire tank in horrible in town traffic, freeway runs the trip computer be within .2-.3 MPG of hand calculated.

I only used trip computer figures as I was at all sorts of different pumps and stations in Tennessee and Georgia.

 

[RationalRussian]

Great write up and calculations. Most automakers purposely make the E85 tune complete pooey to force you to use conventional gas. If you really cared you might be able to locate an after market flash tune for your particular vehicle. If you use enough E85 you might negate the cost from the improved mpg.

 

[edwardh1]

e85 increases food prices

 

[pezzy669]

Originally Posted By: edwardh1
e85 increases food prices


I see this argument frequently on my google searches. Do you have reliable sources (give me at least 3) to back this up? I don't argue based on hearsay, I argue based on facts.

 

[turtlevette]

Originally Posted By: pezzy669
Originally Posted By: edwardh1
e85 increases food prices


I see this argument frequently on my google searches. Do you have reliable sources (give me at least 3) to back this up? I don't argue based on hearsay, I argue based on facts.


It ruins your lawnmower and car. It spies on you and makes your head explode. These are right off the oficial old [censored] website.

 

[01rangerxl]

My truck has been filled with E85 off and on for about 11 years now. Sometimes nothing but E85 for months at a time, other times a single tank between tanks of 87.

It's usually about a 20% reduction in fuel economy for my truck, but it runs great on it and definitely feels more powerful. The engine is super smooth and quiet at idle with E85 too.

The fuel system on my truck is all original aside from the filter, no issues with E85 there. The engine has never been opened and runs great, so no issues there either. I did have to replace the y-pipe pre-cat assembly about 40K miles ago, but I think that was from towing frequently with a 3.0L, not from using E85.

I don't use it unless it's convenient and the price is right. If my truck didn't run better on it, I probably would not use it at all given the hit to fuel economy. Maybe after a couple tanks your car will run better on it, but if it's not convenient I wouldn't bother.

 

[TiredTrucker]

I have used various blends from E10, E15, E20, E30, thru E85. My only appreciation for using any fuel selection is based solely on cost per mile. I pretty much know the mpg I get from each fuel. I can therefore make fuel selection based on pricing and the associated mpg and determine what is going to the least expensive per mile to use. Not like it fluctuates that often and I am switching blends tank to tank, only seasonal. Right now, compared to premium at $2.54 in my area, and E85 at $1.59, it is a no brainer.... E85 would be the choice. But I am not limited to using premium, so right now, E15 regular offers the best choice for me right now. 5 - 10 cents a gallon cheaper than E10 ($2.03), and virtually equivalent mpg from either one of them.

 

[pezzy669]

Hey guys sorry for the delayed response, very much appreciate the feedback. Here are my observations now 4 tanks in.

1) Performance pretty much returned to normal sometime during the 2nd tank of E85, guessing the car needed a bit of time to adjust to adapt to the E85.

2) Exhaust smells sweet now and it does not seem to have that foul cold start exhaust smell like gasoline does.

3) I think it is doing some housekeeping on internal deposits, first two tanks absolutely loaded the rear of my white car with soot. The past 2 tanks it has been reduced quite significantly.

4) Mileage is about as expected. 20-21 is easily achievable on the freeway (vs 27-28 on Premium) and 11-12 in 100% city (vs 16-17). But my local E85 station it is $1.89/gal vs $3.05/gal so it is still financially beneficial to run E85 in my case.

5) Local station is one of very few intown ATL E85 stations and they only have 1 E85 pump so its a freakin zoo from [censored]. Last fillup I had a 'I got here first' jockeying for the pump moment with a gentleman in a Suburban who told me I was going to ruin my car running E85, he promptly put his tail between his legs when I invited him over to look at the sticker on the gas door. By the time I pumped my 15.8 gallons (~3-4 minutes) the guy in the Suburban and 2 Escalades were waiting for the single E85 pump. Both Escalade drivers were nicer about the interaction and were surprised Mercedes made a flex fuel vehicle.

Unless prices change drastically I am an E85 convert, it still works in my financial favor so until Premium drops in price or E85 goes up I am running strictly E85.

 

[GMBoy]

Originally Posted By: pezzy669
Hey guys sorry for the delayed response, very much appreciate the feedback. Here are my observations now 4 tanks in.

1) Performance pretty much returned to normal sometime during the 2nd tank of E85, guessing the car needed a bit of time to adjust to adapt to the E85.

2) Exhaust smells sweet now and it does not seem to have that foul cold start exhaust smell like gasoline does.

3) I think it is doing some housekeeping on internal deposits, first two tanks absolutely loaded the rear of my white car with soot. The past 2 tanks it has been reduced quite significantly.

4) Mileage is about as expected. 20-21 is easily achievable on the freeway (vs 27-28 on Premium) and 11-12 in 100% city (vs 16-17). But my local E85 station it is $1.89/gal vs $3.05/gal so it is still financially beneficial to run E85 in my case.

5) Local station is one of very few intown ATL E85 stations and they only have 1 E85 pump so its a freakin zoo from [censored]. Last fillup I had a 'I got here first' jockeying for the pump moment with a gentleman in a Suburban who told me I was going to ruin my car running E85, he promptly put his tail between his legs when I invited him over to look at the sticker on the gas door. By the time I pumped my 15.8 gallons (~3-4 minutes) the guy in the Suburban and 2 Escalades were waiting for the single E85 pump. Both Escalade drivers were nicer about the interaction and were surprised Mercedes made a flex fuel vehicle.

Unless prices change drastically I am an E85 convert, it still works in my financial favor so until Premium drops in price or E85 goes up I am running strictly E85.






Thanks for your info - I've not tried E85 yet in my flex fuel vehicle but if it appears to you like some cleaning went on I sure am interested in a few tanks just for that.

 

[THafeez]

Great write up!
+1

 

[John_Conrad]

pezzy669:

your actual cost to use the E85 based on the loss of mileage you provided is this:

$1.44(what you paid for E85)/.2635(your percentage loss in mileage)=$5.46

you now compare your actual cost of $5.46(taking into account mileage loss) vs the $2.27 price of the premium.

this is how you compare apples to apples.

if i misunderstood something in your original post, please let me know and I would be glad to refigure the "actual cost of the E85 taking into account the mileage loss so that a better comparison can be made taking into account the energy value loss from using the ethanol.

 

[turtlevette]

Originally Posted By: John_Conrad
pezzy669:

your actual cost to use the E85 based on the loss of mileage you provided is this:

$1.44(what you paid for E85)/.2635(your percentage loss in mileage)=$5.46



No. Its 1.44 * 1.26 = 1.81

Come on man. Think about your calcs.

 

[edhackett]

Originally Posted By: pezzy669

2) Exhaust smells sweet now and it does not seem to have that foul cold start exhaust smell like gasoline does


Revel in the new found levels of aldehydes and ketones in your exhaust. Toxins and carcinogens all. Those of us who breath the air don't salute you.

Ed

 

[turtlevette]

Originally Posted By: edhackett
Originally Posted By: pezzy669

2) Exhaust smells sweet now and it does not seem to have that foul cold start exhaust smell like gasoline does


Revel in the new found levels of aldehydes and ketones in your exhaust. Toxins and carcinogens all. Those of us who breath the air don't salute you.

Ed


Let's do this, Mr ed. I'll burn ethanol indoors and you burn gasoline. Make sure you close all your windows. Seal your house up tight.

Then well see who lasts longest. Let me know when you're ready to begin.

 

[pezzy669]

Originally Posted By: turtlevette
Originally Posted By: John_Conrad
pezzy669:

your actual cost to use the E85 based on the loss of mileage you provided is this:

$1.44(what you paid for E85)/.2635(your percentage loss in mileage)=$5.46



No. Its 1.44 * 1.26 = 1.81

Come on man. Think about your calcs.



Yup! Thank you for making the correction to this terrible math while I was offline.

 

[pezzy669]

Originally Posted By: edhackett
Originally Posted By: pezzy669

2) Exhaust smells sweet now and it does not seem to have that foul cold start exhaust smell like gasoline does


Revel in the new found levels of aldehydes and ketones in your exhaust. Toxins and carcinogens all. Those of us who breath the air don't salute you.

Ed


Look I am not trying to debate emissions quality, but if you want to go there I definitely will. I'm just trying to give my user experience of using E85