DansSlk

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UK-C200, yeah UK MPG so that does make it look higher to somebody in the US reading it as figures they would see.

The fuel the UK 55 uses is 98 RON so again that needs conversion to be accurate in the US.

The figures i quoted are only really of any use to Legin because without conversion you can just cross them over to the US figures.

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etyu

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1 Imperial gallon = 1.20095042 US gallons

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Eddy

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Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package
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bee210

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I just got back from a trip to Lake Tahoe in my SLK55. As measured by the in-dash gauge: on the way up the hill from Modesto, I got around 22 MPG; on the way down the hill to Mountain View, I got around 25 MPG.

dsb

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I've definitely got around 25-26mpg on the highway driving conservatively. However, I usually average closer to 17-18mpg with mainly city driving. It is absolutely possible to get decent mileage out of the 55 but you have to drive with a light foot. BTW, I think I got that mileage at closer to 70 mph.

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anjs

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Well my UK figures

Over 7,000 miles the average is 20.1 MPG. That is with all styles of driving. One long motorway trips I have had it over 30 a couple of times.

cyberdrakon

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i've gotten 26 mpg in the US on my SLK55. My 'normal' highest is 22, and my 'normal' lowest is about 13. highest occurs right under 70 mph. elevation was low though, don't remember what it was.

regarding that contract regarding the gov't, they should check with corvette, they are getting better numbers than us, with more liters.

cyberdrakon

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Anyway, the meter in the SLK is not really that accurate, due to the way it calculates the mpg, it should only be a rough guide.

DansSlk

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Yeah it works both ways, Maserati's 4.2L returns 7 MPG around town

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Legin

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Good info guys. Another question, is 95 ron ok with the slk 55 uk spec, appreciate 98 is likely better for power but is the ecu trained to deal with 95 which is nearer to 96 more often than not at the pump anyway.

DansSlk

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No, 98 is the fuel you should run the car on.

Anything lower is for emergency use and you cant use all the throttle, please don't take this the wrong way because for all i know you could be royalty but if you looking for ways to run a SLK55 relatively cheaply then your better off buying a smaller engined SLK because trying to run a 55 on pennies will bite you in the ass big time.

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SLKfor2

I have been following this thread, and each time I read it, the above sentiment has been coming to my mind. The cost of fuel is relatively low in relation to maintainance, depreciation, insurance, etc on the SLK. Particularly the SLK55!

As far as fuel efficiency goes, I am no expert, however, I feel as I am at least as knowledgeable as most consumers, if not more. My daily driver is a 2006 Civic Hybrid. I often get over 60MPG with that vehicle, and have averaged over 50MPG for the last 60,000 miles. I can say that with my SLK 280, 30MPG (with minimal stop and go) is attainable by anyone who is determined to do it. You must drive it like fuel is gold and the ONLY goal is to use the least fuel possible. I would guess that mid to high 20's is certainly attainable in the SLK55 given a similar scenario, and that seems to be what most SLK55 owners have experienced.

Sincerely though, with all due respect, what's the point of driving an SLK if fuel economy is that much of a concern?

Legin

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No offence taken and none meant in what I say. Thing is I make the stuff so I have a slightly different perspective to most people on fuel. Oh Im not quite royalty your right. What happens if you run 95 ? does the eng mgt retard the ign based on knock sensors ? A 360Bhp 5.5 ltr is a low specific output to require 98 + , is it noticeable the difference on the road.
Also what is the wording in the user manual .
Apologies for all the questions

Legin

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Who said anything about economy. My question was what are the consequences of running 95. If you get 60 mpg hybrid and 30mpg from slk 280 then why didnt you buy the 200 ? There is no correlation between octane and how I drive, merely throwing cash potentially down the drain.

My last car was a 2 liter Honda supercharged non intercooled Lotus with 300 Hp mapped myself, this ran 95 ron road and 99 track, performance is identical on either fuel has not trained to run knock retard. So I say again a 5.5 360hp should be able to run all day long on 95 but if it cant I would like to understand why and the consequences.
Anyone running there,s quite happily on 95 ?

UK-C200

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Hmmmm - so my reference - the MB owners guide - specs 98 RON/88 MON for the AMG, which equates to 93 Octane in the states. In the states, you don't have the option of a 200, only the 6 cylinder's make the cut, so the 280 is the theoretical "best" in the land of fuel consumption.

Th manual also states :
"If the recommended fuel is not available and only as a temporary measure, you may also use premium unleaded petrol, 95 RON/85 MON. This may reduce performance and increase petrol consumption. You must avoid driving at full throttle."

I read that as the ECU is going to retard the knock, but MB are saying it's a bad idea. I'd suspect it's simply down to MB AMG optimizing the engine for a very narrow fuel band tolerance.

As to the consequences? I'm no expect, and Dan is the one I listen to. I've heard third hand that a CLK55 owner in the states had a blown engine, and the dealership refused to replace it under warranty after testing the fuel in the car, and finding regular unleaded in it. Not a clue if it's true or not.

Legin

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Pretty conclusive then, 95 Ron risks detonation and therefore engine damage. Good reason to avoid it. Thanks for the info

DansSlk

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Nothing to do with fuel economy, i was simply stating that if Legin was making 95 references in order to save money (and it appears he was not) then he was in for a big surprise when it comes to servicing, tires, etc, etc.


UK-C200 answered this wonderfully, I'm sure if MB wanted to have the engine run on 95 they could do that but AMG have tuned the engine for 98 and the ECU has been told as much so thats what it expects.

There is a noticeable difference between 99 (v-power) and 97 on the road so i can only imagine what running 95 would do to it, you see it from a fuel perspective and i see it from an engine/electronics perspective, the ECU knows its baseline fuel and has a certain range that it can adjust in both above and below that (I'm sure you know how knock sensors work, so i wont bore you with that) the point being it means MB can say if you need to you can run the car on XYZ fuels for a short period since at the end of the day its a road car and everybody gets stuck now and then so allowing it only to run on the most exotic stuff they could find would be a bad idea but you of course pay a price for that flexibility and in this case its economy and throttle range.

Anything below the allowed range and at the minimum you will get a CEL (limit of adjustment range code) and probably a shutdown as the ECU moves to protect the engine, worst case is she goes pop and you end up like that CLK owner, I've not heard that story personally but the logic is sound, MB will refuse warranty claims on the grounds of incorrect operating fluids (I've seen them do it) and the cost for a new engine without labor is £30k.

I can see you have made your mind up already but i strongly suggest you do stick with the 98, just as an aside this can happen if you do the exact opposite and run something super exotic in it (not so much the detonation issue obviously but you will hit the upper adjust limit).

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