Which MPH gives the best MPG ?
Another thing is Ethanol , some areas may not have it and they would get better mileage..
Places that have ethanol can take off 5 to 10% in their mileage.
There are actually tons of threads on this forum w/ E550 figures from dozens of owners. Everyone can't be cook'n the books

So it has to be the motor that change the mileage.
If people are going off the cars mileage display and not fill up's and real numbers that will be most of the problem.
I have never seen one on the money yet. I filled up today and mine was off -.8 miles per gallon so
it showed 29.9 to the real 29.1 mph that it was.
I check mine everytime.
Last edited by 2slowcdi; Apr 22, 2011 at 04:56 PM.
In the 7-speed gearbox the 5:th is 1:1 with both 6:th and 7:th being overdrives.
I get circa 7.3 mpg in bad traffic and around 13.7 mpg on the highway...seem to have a bit of a lead foot...!
Brgds * *
There are actually tons of threads on this forum w/ E550 figures from dozens of owners. Everyone can't be cook'n the books

Brgds
If people are going off the cars mileage display and not fill up's and real numbers that will be most of the problem.
I have never seen one on the money yet. I filled up today and mine was off -.8 miles per gallon so
it showed 29.9 to the real 29.1 mph that it was.
I check mine everytime.
Brgds
Last edited by OK55; Apr 23, 2011 at 07:33 AM.
The Best of Mercedes & AMG
I fill up at one pump at two different stations so I have the same numbers from time to time.
Most pumps are set low but the low is less that 6oz's in five gallons.
If you have every seen the red looking 5 gallon milk jug with the glass window at the top to make sure that the pumps are set its not much one way or the other.
One of my first jobs years ago I would calibrate gas pumps , you could get in just as much trouble for a pump that was giving to much gas as to little.
The seventh gear along with the diff gears will give the same final drive ratio within a few percent of the over drive of the five speed transmission with the rear end gear ratio that the five speed cars have.
This is the case with most cars its to keep the rpm in the Sweet spot for the motor.
The easy to see is with the same tires and same air pressure the rpm at a given speed will be almost the same.
This is the case with most cars its to keep the rpm in the Sweet spot for the motor.
The easy to see is with the same tires and same air pressure the rpm at a given speed will be almost the same.
E500 5-speed 306hp 5th gear 0,83, rear axle 2.82.
(European versions.)
Can't find the rear axle ratio of the 306hp E500 7-speed though..
Nevertheless.. The newer engines are turning at a lower rpm according to the above..
Most pumps are set low but the low is less that 6oz's in five gallons.
If you have every seen the red looking 5 gallon milk jug with the glass window at the top to make sure that the pumps are set its not much one way or the other.
One of my first jobs years ago I would calibrate gas pumps , you could get in just as much trouble for a pump that was giving to much gas as to little.
An error of 6 ounces in 5 gallons dispensed by pumps is about 1%. And since this doesn't take into account the effect of temperature changes - a 13 deg C change could change petrol volume by up to 0.5% - I believe the total possible error is significant in comparison with the 2.7% difference.
Brgds
1st 4.39 ,,,,,,,,,,,,five speed
2nd 2.83 ,,,,,,,,,,,,1st 3.59
3rd 1.92 ,,,,,,,,,,,,,2nd 2.19
4th 1.37 ,,,,,,,,,,,,,3rd 1.41
5th 1.00 ,,,,,,,,,,,,,4th 1.00
6th .82 ,,,,,,,,,,,,,,,5th .83
7th .73 ,,,,,,,,,,,,,,,,Axle ratio
Axle ratio ,,,,,,,,,,,,,2.62
2.47
I had only looked at the AMG E55 and the E320 CDI five speeds and found one difference first gear, on the AMG its 3.59 and on the CDI its 3.60 everything else was the same.
So after looking at the AMG E55 gasser and the CDI diesel ,,,, I should have looked further.
So it looks like all the 7 speed transmissions are geared higher.
And this will help in mileage.
I got my diesel for reilability and longevity not mileage , but it does not hurt to get better mileage.
Last edited by 2slowcdi; Apr 25, 2011 at 09:18 PM.




To answer this question from an engineering perspective, what we would need is a graph of the efficiency of the engine as a function of RPM, as well as aerodynamic data of the car. Slower is not always better once you factor this in. If we wanted to get all technical, I'd also ask for drivetrain losses as a function of tranny speed / gearing.
Actually that's when your car gets the WORST efficiency. You can idle your car to Empty before going 1m.
The best MPG is going to come when the graph on the dyno has a flat tq and hp line.... so we would have to look at the stock dyno chart for our cars to see where exactly that sweet spot is.....
Anybody got a stock dyno chart for a w211 e500 ?
Horsepower 302-hp @ 5,600 rpm
Torque 339 lbs.-ft. @ 2,700 rpm
Fuel economy city 17 mpg
Fuel economy highway 25 mpg
Fuel tank capacity 20.6 gal.
WHY on earth didn't I make this move before
Oh ... this is in an E350.
Last edited by Heatwave; Apr 27, 2011 at 09:14 PM.
(.....i'm not driving 55mph either!! ...but I don't want to be measuring my gas milage by the foot either...)
Just understand that aerodynamic drag increases a the square of speed, i.e. doubling your speed increases drag 4 times. Fuel burned is a function of work performed. Faster you go, you do more work to overcome drag and your engine turns faster in any event.
As for MPH vs MPG, I'm not sure where the sweet spot in my car falls, but at 84 MPH, I'm around 40 MPG. I've started at 33.8 (where the computer defaults) and watched it climb to over 40; my last trip ended at 40.3 MPG on the display.
I've found the displayed figure to be a tad optimistic by 1-2 MPG based on hand calculations, though.
I haven't actually tested this, but when I run at 75, the computer seems to settle out closer to 38... so it just makes me wonder how the thing calculates the MPG since I doubt there's an inline flowmeter in the fuel system.







