55k owners, what kind of MPG are you getting? and why is mine so horrible?
My car is completely stock engine wise minus a resonator delete but even when I baby it on the highway the best I have seen is 11 MPG, around town sometimes 8-9 mpg
The car runs smooth as butter, no CEL and everything seems to be in order. This isnt my first V8 mercedes ( 210 E55, C43, 55 swapped 43, etc) I know the V8's dont get the greatest gas milage obviously, but this is just crazy considering its the same 55 motor just with a supercharger slapped on it.
Also as I stated above, on first start of the day if I reset my odomoter and average mpg the "after start" says something like 6mpg and the "after reset" was closer to 11

Any ideas whats causing this? maybe a bad MAP sensor, or is this truly the mpg we get? I know my buddy with a modded W211 E55 gets 20+ on the highway
Thanks guys! - Dom
My prior car was an E55. It got far better mileage but no supercharger. That makes all the difference.
But the CL55 mileage is still better than my Ferrari and almost as fast
While driving from Flagstaff Az to Las Vegas NV it got 27 mpg but it was downhill most of the way haha.

"after start" was saying 3.5 mpg at the same exact time
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My prior car was an E55. It got far better mileage but no supercharger. That makes all the difference.
But the CL55 mileage is still better than my Ferrari and almost as fast��
And hah thats awesome! pics of Ferrari!?
I'm so shocked at how cheap you can pick these up for now, so much car for the money
Swapped in fresh spark plugs a month or two ago, will give 02 sensors a try
Not bad!
The Best of Mercedes & AMG
You can also reset the "after start" computer when you start rolling. At a standstill it begins your average at 2 mpg. Rolling it starts around 16mpg. Straight hwy driving should yield you 20mpg easy.
My mileage has not really changed over 10 years of ownership. When I first got the car I was surprised at how much less mileage I got than my E55. I took it to the Mercedes dealer and they fully checked it out and he told me the mileage was "within acceptable parameters". He essentially told me the difference is "the supercharger, stupid." I will admit to trying to set a land speed record leaving every red light. Ya think that might affect the mileage a little?

However, on my best day on the highway with long trips and only going downhill, I have never got over 19 MPG.
Here's the 612. Yes, you can literally get these now for $200K off of original sales price. But you can also spend that on maintenance and repairs if you are not careful. I laugh when people comment on how expensive CL55 parts are!

with truly trying driving sluggish and coasting down hills I was able to get 19.5

That was all highway driving, after some around town miles it averaged down to 15.7

Not bad at all! This is with resetting the trip while in motion, This morning I reset it at idle and without moving it said I was getting 3.5 mpg again so I'm not sure whats up with that but definitely satisfied!

The "European tune" or the "Level One" tune from some of this site's vendors, with an otherwise stock car in maintained condition, removes this restriction, should give more power and better gas mileage all other things being equal. Can any of the Forum participants attest to this?
3.5 is a good range for a MBUSA CL55. If it dips below that one has a problem. These are often caused by wear in the supercharger pulley/belt system, tensioners, etc. as much as the factors that OP have mentioned.
I have another M113 car sans supercharger. It consistently gets in the 5-6 mpg at startup despite having the nanny tune. One of the reason maybe, but this is counter-intuitive, that it is a 3 valve per cylinder version rather than the 4 of the AMG engine.
I normally get 20-22 mpg on the highway if I use the CL55 cruise control for 65-70 mph. However, even with the MBUSA nanny tune I notice that cruise control at 90 mph yields a higher mpg (93 octane Shell, Techron once a month) but I don't need any tickets.

My wife's 013 "new model" GLK 350 4x4 gets 24 mpg on the highway so I am not complaining.
Thanks

Then you have to have a system to return the car to the stage 1 or what I call the Euro tune. I don't think these are "stealth" tunes. The MB dealership will pick up on these right away. For some it does not matter since they sell nouveau-riche tuning packages themselves.
I know Euro-Charged and some other used to offer E55, Cl55 tunes and accessories such as pulleys and belt-wrap kits.
My wife feels that the CL55/65 of the 2003-2007 has a classic body style. One day people will recognize it value. I remember when you couldn't give away a Ferrari Dino.

PS
Thanks RonCL55








