Roehl

So what can we do to increase gas mileage on the E500/550. It seems we all average 21-23mpg on the highway.

stingray71

Well, mine is an E350, but the principles are the same. There may not be one "silver bullet", but rather a lot of small things that can be done. For example:

1. Correct tire pressure - reduce road friction
2. Clean air filters - more efficient combustion
3. Clean Mass Air Flow sensor - more efficient combustion
4. New/Good Quality Spark Plugs - more efficient combustion
5. Freeway Driving Habits - Use Cruise Control especially when terrain is more level. Smooth out acceleration.
6. Use Comfort Mode (C) for transmission setting
7. Correct premium octane fuel (91-92 octane)
8. Occasional use of fuel system cleaner as recommended by MB e.g. Techron

I'm sure there are others, but these are the ones I can think of.

Jen_Kenne

9. Always drive down-hill, never up-hill.

flossinlo05

I just posted how bad my day went...and it was bad, but I thought I would share some of my milage stats...

I've had my car for (original reset): 3203 miles, 88.58 hrs, 36 mph and 22.7 mpg.

For my road trip today: 1175 miles, 16.05 hrs, 74 mph and 26.8 mpg....thats door-to-door.

I got gas three time. Once before the trip and twice during...the milage range per tank was about 525-550.

chokaay

That's amazing! Is that in an E350 or E550?

I drive an E350 and after reset, I'm averaging around 17-20mpg now (around 350 mi/tank or a little more). Hopefully my mileage goes up!

Jen_Kenne

I just made a drive from Jacksonville to Fort Lauderdale -- 305 miles door to gas station. I filled up as I arrived in town and it took 12.1 gallons. That works out to 25.20 mpg. Half of the drive was with cruise set at 78, and the other half without cruise, with occasional bursts to higher speed, and one 10 minute delay where we came to a near stop. That seems typical for my 2004 E500. YMMV.

stingray71

So, I ran my own test on a tank of gas and here are the results:

Total mileage: 442
Gas at refill: 17.887 gallons
The computer average was 26.3 mpg
The actual average was 24.71 mpg

This means the computer was about 6.25% too high
I'm not disappointed in the average of 24.71 mpg since this was the combined mpg and as you can see the average speed was 35mph.

Vik888

I think the important statistic here is also the average speed. If you're averaging 40mph for example, do you really expect to get the freeway mileage or better advertised for your car?

nopcbs

I'd be pretty happy with your 24.7 mpg at this point. You average speed is not much different from mine, but it does beg the question of how much stopping/starting is in it vs. just steady slow cruise.

The mpg gauge is surprisingly inaccurate at 6% optimisitic. That would be almost a gallon of fuel and very unlikely to be due to the vaguries of topping off a fuel tank consistently.

I have never heard anyone report a lower readout mpg than they get by calculation. It's always higher. I think MB fudges a bit in their calculation.

- GRL

stingray71

I'm happy with 24.7 combined as the EPA estimate was 20.
My commute is about 40 miles highway and 20 miles of slow driving. I know the highway mileage is over 30mpg.

sunnySD

I've got about 1500 miles on my 2009 E350 and just calculated today on my drive between San Diego and Santa Ana. Trip was 319 miles, maybe 25 miles of it on streets. 70-80MPH keeping up with traffic with occasional slow down to stop in SoCal traffic.

Trip computer said I got 27.6MPG and my hand calculation was 26.2MPG.

I'm driving in S mode. Is gas mileage better in C mode?

Vik888

Depends on how many starts you do from a low speed or stop.

S starts in 1st gear every time = higher rpm = worse mileage, better pick up
C starts in 2nd gear = lower rpm = better mileage, poorer acceleration.

Thus, fun = bad mileage, not fun = good mileage.