The M113 4.3 gets fantastic mileage. With the cruise at 70 and the AC engaged, 4 and half hours later I'm showing almost 29 MPG.



The C43 has different cams than my CLK430. The heads are the same part numbers, but looking at the roof of the exhaust ports, it’s obvious someone with a die grinder has been at work. I have no idea which throttle body the C43 came with (the early 69mm, or the late 74mm). Still, it hard to picture there being much difference in economy.. . . if one can fight the urge to keep the speed down.

 

the 5.5L AMG gets even better gas mileage on hwy b/c its high torque / tall gearing. With a few minor changes 31+ mpg on hwy is easy, 25+mpg city also not too tough.

The M113s are very efficient because of their dual intake, single exhaust value design as well as dual spark plug per cylinder, and as a results, its emissions are also very good considering its displacement.

M104 on the other hand... its pretty bad for a 6-banger haha.

 

dude tell me about it, haha o well...it pays off when u punch the gas down!

 

From a performance standpoint though you can extract more power out of a single spark plug 4 valve per cylinder engine but its heavier on the fuel consumption (new C63 is another example of that, more power but again fuel consumption is terrible). Thats the trade off.

A few things you can do to improve fuel consumption is try to lean up the mixture as much as you can since they run on the rich side. K&N filters help a tad, and royal purple in engine & diff will give help out also.

Other than significant weight reduction & reducing the rotating mass throughout the drivetrain (flywheels, pulleys, carbon driveshaft, etc etc), theres not much else you can do to improve fuel efficiency, an M104 will never be as efficient as an M113 V8 no matter how hard you try just b/c of its design.

 

+5!

Im doing 10-9 MPG

Thank god gas prices are going down...

 

Hah, I remember a while back posting my excellent mpg figures for the C43 going cross country and there was nothing but disbelief and skepticism among the responses I got. Nice to see some good photo and anecdotal evidence to support reality. Just drove to Austin this weekend, and averaged 26 mpg with mostly freeway but slightly mixed driving. Most of the trip was spent at 75-77 mph. I would say that around town (purely city driving) I end up only getting 20-22 mpg depending on how hard I hammer the loud pedal (not that often).

 

I’m not sure which 55 you’re referring to. If it’s the CLK55 versus the CLK430, I’m having a hard time understanding why the 55 would have an increase in low speed ‘efficiency’.

If we can agree (1) the force required to overcome drag (the density of the earth’s atmosphere) is the exact same for both cars. And (2) weight isn’t much of an influence at steady speeds – drag (the vehicle’s CD) is what matters. Then I believe you’ll understand my quandary.

Since both the CLK55 and the CLK430 both have the same CD - .31, the power required to sustain a constant speed is the same for both vehicles. For the 55 to get better fuel economy, the engine must be more ‘efficient’ at making the energy required to overcome drag. I say the ‘engine’ because the CLK55 transmission has the same fifth gear ratio as the CLK430. The final drive ratio in a CLK55 is one point seven percent lower than a CLK430 (2.82 versus 2.87). My first problem is I have a hard time believing an engine of the same design, that is over 27% larger (5439cc versus 4266cc), can attain better fuel economy by simply turning less than 2% slower. The 27% on one side of the equation is so much larger than the 2% on the other.

Also, the 55’s extra torque may be desirable, but for fuel economy, that 80+ lbs/ft of additional torque doesn’t come into play. In fact, for MPG at cruise, I don’t believe torque matters. *I believe* HP (torque over time) is the key. I’m not going to pretend to know how much HP is required for a CLK to cruise at 55MPH. HOWEVER, I can tell you that per Ford, their Flex (which has a CD of .355 - higher than the CLK's .31) requires less than 9 HP to cruise at 55 (not accelerate to, but sustain a speed of 55 MPH). You can see that in an article at Edmunds. (http://blogs.edmunds.com/greencaradvisor/2008/07/ford-flex-may-have-superb-aerodynamics-but-fuel-economy-is-nothing-special.html).

With that background, for the 55 to achieve better fuel economy, it must be more efficient than a 430 at producing something less than, say 12 HP. That’s where I get lost. A 55 is more ‘efficient’ at producing 12 HP? Efficient as in consuming fuel to produce? Both the EPA and MB USA claim the CLK430 and the CLK55 have the exact same highway fuel economy. If that’s the case, how can one engine be measurably more efficient at a steady speed of 70 or so? I can break 30 MPG, but the freeway had better be wide open, and I have to keep the speeds under 65 MPH. Are there 55 fuel economy posts where owners are claiming 30+ MPG?

As for your other post where you implied a 4-valve/single plug ‘design’ uses more fuel than the M113’s 3-valve/dual plug design, its not the number of valves or plugs. If that were true, econoboxes wouldn’t use 4-valve heads (which are more expensive to produce). The reason the M273 and M156 V8’s use so much more fuel is the head’s intake and exhaust port size. Large ports at low engine speeds result in low intake and exhaust velocity. The lower port velocity (at low revs) results in poorer efficiency, which shows itself as poorer economy. The trade off is in the upper rev range.

Whoops. I can see the red light is on and my time is up. Please tip your servers. They may be dressed like hookers, but they have families to feed. . . . .

 

go ahead and try it in real world testing, see for yourself

I've gotten as high as 34.5mpg on hwy from w210 E55 (granted that was driving like a grandma steady at 70mpg w/ no fluctuation). Avg mileage was 31mpg w/ overtaking & etc. City around 25-26 avg.

The 55s can be extremely fuel efficient if you know what you are doing, but only if you mod for efficiency, if you slap in bigger injectors and don't mod the car properly, MPGs can actually go down. In fact, many of these new big displacement V8s are getting phenomenal MPGs such as the Z06 which gets roughly 31mpg on the hwy and etc. It has to do with the fact that they are so torquey that it requires very little throttle input to get the car moving and keep it moving so it actually consumes very little fuel in relation to the amount of power it provides.

 

are you omeyhomey?

 

I thought you already knew that SVT , yes , I thought everyone knew that.

 

The W210 E has less drag than a W208 CLK. It has a CD of .29 versus the CLK at .31. The E should get better steady state economy, but I don't see how an E55 is supposed to get better economy than an E430. According to the 2002 Mercedes-Benz press kit, MB USA seems to agree with what I'm saying.

MB USA said the E55 was rated at 17 in the city and 24 on the highway. They say the E430 was rated at 18 in the city and 25 on the highway. If increasing the peak torque rating increases the mileage efficiency, then the E55 with 391 lbs-ft should have better mileage than the E320, which only has 221 lbs-ft. The E320 and the E55 both have the same 0.83:1 fifth gear ratio, but the E320 has a 3.07 final drive, versus the E55's 2.82 - avantage for the 55. However, the E320 is rated at 20 in the city and 28 on the highway. That seems to indicate something other than peak torque is at play.

As for your saying you've gotten "as high as" 34.7 MPG in a W210 E55 - I wouldn't confuse that with actual fuel economy. That’s why I showed you a photo where my trip meter said the car averaged 28.9 MPG for over three hundred miles. Here's an "as high as" photo from my car, which also has nothing to do with real mileage.

 

I said with mods you can get up to 25/31, Stock E55 got roughly 17/24 and with mods you can get more mpgs out of it. I am talking over 100 miles + , obviously not short term/ My City avg of 25+ was over a full gas tank of 300+ miles. Its very easy to get more fuel efficiency with the right modifications but you have to know what to do.

What I mean "as high as" is if I drive 100% steady state rpm @ 70mph and do not fluctuate at all over say 100 miles, I got that much but nobody drives like that, most people fluctuate rpms a bit and over take cars occasionally & etc, that comes out to roughly 31mpg. If you are just talking about going real fast then letting off gas you get get 50+, thats not what I'm talking about. Real long term MPGs of 25/31 are very easy with the right mods.

 

Actually, what you said was "the 5.5L AMG gets even better gas mileage on hwy b/c its high torque / tall gearing." My point is simply that a 55 is not going to get "even better gas mileage on hwy" than a 430. I've posted a photo of my 430 averaging 28.9MPG over 300+ miles. Now you're talking about going fast and coasting. Yeah, right, I hit the reset button and "coasted" for 300 miles.

If you've personally driven an E55's that gets over 34MPG, and believe E55's get better mileage than 430's because of the "extra torque", that's your unique perspective. When some E55 owners post "my E55 gets 35MPG too", and you can explain how "peak torque" increases fuel economy, I may change my perspective. Until then, I find your position to be beyond the realm of believability.

 

what kind of city?
i think maybe under 200 miles a tank if strictly in san francisco. maybe i'm just too impatient in cities .. even in my wagon, with 5 cylinders, i get only 13 mpg in sf..