Been reading of some discrepancies over on the W211 forum, especially the CDI's, about the MPG dashboard readouts being, shall we say, optimistic.
http://www.benzworld.org/forums/w211-e-class/1725554-mpg-reading-overstated.html
So, I wondered if this applied to the W220's as well.
Given that I've been driving the S600 TT as my daily driver, I figured it should be the first candidate for examination. Here is my test methodology.
1.) Ensure the tires are properly filled up.
2.) Fill up the gas tank.
3.) Start the engine.4
4.) Reset the MPG counter in the menus (on my car, that's three menus down).
5.) Reset the trip odometer.
6.) Go driving.
7.) At next fill-up, take down what the computer says, "after reset". Compare them to calculation from actual miles traveled from the trip odometer vs. gallons of gasoline it takes to fill the car back up again.
8.) Rinse and repeat.
So, here we go with some examples from some receipts that I had kept.
Late December 2016, after 400+ miles of pure highway driving, averaging 78 MPH:
Computer readout: 19.3 mpg
With calculator: 19.53 mpg
Again, late December 2016, 350 miles of pure highway driving, averaging about 68 mph:
Computer readout: 20.5 mpg
With calculator: 20.67 mpg
March 2017, combined driving, 320 miles:
Computer readout: 13.6 mpg
With calculator: 14.3 mpg
Early April 2017, mostly highway driving, with some city driving, 360 miles:
Computer readout: 17.0 mpg
With calculator: 18.2 mpg (hmm...big difference here....)
Mid April 2017, mostly highway driving, with some city driving, 370 miles:
Computer readout: 18.7 mpg
With calculator: 18.2 mpg (hmm...this time it's slightly lower)
Last week, pretty much all city driving, 280 miles:
Computer readout: 11.3 mpg
With calculator: 11.7 mpg
The car is a 2003 S600 twin-turbo with the following relevant characteristics:
1.) 19" made-in-China replica AMG-style staggered rims, 8.5" wide in front and 9.5" wide in back,
2.) Michelin Pilot Sport AS3+ staggered tires, brand new, 245/40R19's in front and 265/35R19's in back,
3.) Strutmasters coil-over spring conversion kit, i. e. no automatic lowering of the car at speed,
4.) Costco 93-octane gasoline,
5.) Mobil-1 0W-40 European-spec motor oil from Walmart (with proper M-B brand oil filter), and
6.) Meyle 236.10-spec transmission fluid (it's a 5-speed 722.6).
These examples aren't the only time I've done these comparisons; I do it at every fill-up. These are just a few representative examples.
Initial conclusion: it appears that, most of the time, the computer on this car displays slightly lower fuel efficiency numbers than the calculation at fill-up. So, it's generally slightly conservative, but pretty close to actual. This, I don't mind.
A little side note: just this week, I got those made-in-China junk wheels replaced with some refurbished, genuine-MB, made-in-Germany wheels at all four corners. Turns out the previous owner had gone cheap-o in this area. All four of them had multiple weld repairs for small cracks in the bead area, and two of them had re-cracked and started leaking air. Hmpf....ya just don't do that to a Benz. Anyway, that should not be a problem anymore, and the car looks considerably better now, too.
Back to regularly scheduled program....
The next car to get this fuel-measurement treatment will be the gray S430, also a 2003 model.
http://www.benzworld.org/forums/w211-e-class/1725554-mpg-reading-overstated.html
So, I wondered if this applied to the W220's as well.
Given that I've been driving the S600 TT as my daily driver, I figured it should be the first candidate for examination. Here is my test methodology.
1.) Ensure the tires are properly filled up.
2.) Fill up the gas tank.
3.) Start the engine.4
4.) Reset the MPG counter in the menus (on my car, that's three menus down).
5.) Reset the trip odometer.
6.) Go driving.
7.) At next fill-up, take down what the computer says, "after reset". Compare them to calculation from actual miles traveled from the trip odometer vs. gallons of gasoline it takes to fill the car back up again.
8.) Rinse and repeat.
So, here we go with some examples from some receipts that I had kept.
Late December 2016, after 400+ miles of pure highway driving, averaging 78 MPH:
Computer readout: 19.3 mpg
With calculator: 19.53 mpg
Again, late December 2016, 350 miles of pure highway driving, averaging about 68 mph:
Computer readout: 20.5 mpg
With calculator: 20.67 mpg
March 2017, combined driving, 320 miles:
Computer readout: 13.6 mpg
With calculator: 14.3 mpg
Early April 2017, mostly highway driving, with some city driving, 360 miles:
Computer readout: 17.0 mpg
With calculator: 18.2 mpg (hmm...big difference here....)
Mid April 2017, mostly highway driving, with some city driving, 370 miles:
Computer readout: 18.7 mpg
With calculator: 18.2 mpg (hmm...this time it's slightly lower)
Last week, pretty much all city driving, 280 miles:
Computer readout: 11.3 mpg
With calculator: 11.7 mpg
The car is a 2003 S600 twin-turbo with the following relevant characteristics:
1.) 19" made-in-China replica AMG-style staggered rims, 8.5" wide in front and 9.5" wide in back,
2.) Michelin Pilot Sport AS3+ staggered tires, brand new, 245/40R19's in front and 265/35R19's in back,
3.) Strutmasters coil-over spring conversion kit, i. e. no automatic lowering of the car at speed,
4.) Costco 93-octane gasoline,
5.) Mobil-1 0W-40 European-spec motor oil from Walmart (with proper M-B brand oil filter), and
6.) Meyle 236.10-spec transmission fluid (it's a 5-speed 722.6).
These examples aren't the only time I've done these comparisons; I do it at every fill-up. These are just a few representative examples.
Initial conclusion: it appears that, most of the time, the computer on this car displays slightly lower fuel efficiency numbers than the calculation at fill-up. So, it's generally slightly conservative, but pretty close to actual. This, I don't mind.
A little side note: just this week, I got those made-in-China junk wheels replaced with some refurbished, genuine-MB, made-in-Germany wheels at all four corners. Turns out the previous owner had gone cheap-o in this area. All four of them had multiple weld repairs for small cracks in the bead area, and two of them had re-cracked and started leaking air. Hmpf....ya just don't do that to a Benz. Anyway, that should not be a problem anymore, and the car looks considerably better now, too.
Back to regularly scheduled program....
The next car to get this fuel-measurement treatment will be the gray S430, also a 2003 model.