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Discussion Starter #1
I’ve been trying to decide if I like the “Eco” mode on my new SLK 55. The mode does two things; stops the engine when the vehicle comes to a stop at red lights, stop signs etc. , and engages the 4 cylinder mode when cruising down the highway (both when certain criteria are met). I’m sure I don’t like the stop engine feature at red lights and stop signs. I’m probably too slow to adopt new technology, but I just feel like there is extra engine wear with the constant stop/start of the engine and not warranted for the limited value I get from saving gas. I do enjoy the idea of running on 4 cylinders on the interstate. However I was curious as to how much gas I’d save by running in “eco” mode. So I set up a test that admittedly is not absolutely indicative of what may be seen over time, that said here is what I did;

I set the cruise control on 69 mph on the interstate where it’s flat and no overpasses. I put the vehicle in Eco mode, waited for it to go to 4 cylinder operation, and then reset the MPG readout. I drove 6 miles with no interruptions at 69 mph. In 4 cylinder mode I got 26 MPG. Then I switched off eco mode and drove 69 mph (on cruise control in both tests) and drove 6 miles. In that test I received 25.5 MPG.

So it’s looks to me like there is not a huge incentive to drive in Eco mode. The ECO switch turns on with each startup of the car, although I’ve read that on AMG’s the car restarts in whatever position you last leave the ECO button in, but that’s not the case on mine.

So all that said, I’ll likely spend most of my time driving in the non-Eco mode, unless of course I’m driving a very long distance on the interstate.

I’d be interested in your thoughts on the issue.

Regards
 

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My car certainly doesn't remember the last position - it just kicks up in eco mode regardless.

I don't think a 6 mile run like that is enough of a test to draw any useful conclusions. What I can say is that if I have the car in C+eco, I see higher mpg than if I drive the car in "feel the power" mode (S+range limiting). 25mpg+ (UK) isn't unusual.

Earlier today I did a hard run in S and saw 19 mpg, which might not sound great but it's higher than the 16 mpg I've seen on that run in the R8s. That was keeping the gears mostly 4th and below. Even in S, and allowing it to hunt to 7th, the mpg rises to impressive levels for a motor like this being driven pretty hard.
 

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Hey, you're doing OK without ECO mode. On a new engine with more power and torque than my 06, you're getting 1.5 mpg better fuel efficiency. The absolute best I've seen so far (per the trip computer) is about 24 mpg in ideal highway conditions.

Can you shut off the ECO features selectively and keep the variable displacement but nix the shutoff? Or is it an all or nothing deal?
 

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Discussion Starter #5
I agree 6 miles provides a bit of data, but nothing to draw a total conclusion. I simply had about 12 miles of straight highway so utilized what I had to acquire some data. If one were to assume an improvement of 3 MPG in Eco mode (6x better than I saw in this simple test), that would equate to about 6 bucks over a 300 mile trip. Not enough for me to be interested in the start/stop etc.

I do like the "C" mode, all starts are in 2nd gear, and shifts are generally at low RPM utilizing the engine's torque. I was in C mode both times in the ECO test.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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benny, please update your profile:

Please update your location/vehicle (model and year) in your profile as it helps the members answer your questions which usually are based on that information if you haven’t already.
‘Usercp’ at the top left of page, then ‘edit your details’ on the left side, ‘additional information’ near the bottom, edit your ‘location’ and ‘vehicle’.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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Does this eco thing work with a pioneer aftermarket radio?
ecomode is for the engine, to save fuel, and has nothing to do with the radio
 
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