Benzoid

I'm getting about 17-18 average. I certainly don't baby it around. This is for an average speeds of about 35-40MPH.

If I do the "lead foot thing" I still seem to get 15-16.

23.5 - 25 is realistic on the freeway. (average speeds 60+ MPH). Once you get it moving it doesn't really need much gas.

The worst I've seen is 11 but thats with extremely slow driving in stop / start traffic - with an average speed of < 20 MPH.

What is your average speed during the measurement period?

Dema

I think average speed means not much, unless you drive continuously over 80mph. It's more important how often and how hard you accelerate. Any acceleration when you get more than 3000 RPM will drain your gas very quickly.

etenn

I notice a big drop off in indicated MPG on the display if I idle for any length of time. Computer must use some correlation to time.

Noticed it first after picking up car after motor mount change. No big milage increase (such as being driven) but "time of running" was much higher and gas mileage was really bad...8 - 9 mpg.

Ed

CRB

If you are doing a lot of short trips <5 miles with a cold engine.

Not too good for the engine in general either.

No short trips, no leadfoot then get it checked.

ctouhey

I haven't watched gas mileage that closely since I only have about 1500-1600 miles and the engine is just getting warmed up. I have rarely done any highway cruising to this point -- mostly the close commute or if I get on the freeway, it's either weave in and out of traffic with a lot of acceleration and breaking or I'm sitting in stop-and-go, bumper-to-bumper traffic. I did take one run to Galveston, but it's only 60 or so miles away.

I averaged ~20 mpg or a little less on the Galveston trip, but that was only about half a tank of gas. I don't check that often, but when I look at mileage since start, I usually get 12 - 13 mpg. When I look at mileage since reset (which I have started doing when I fill up), I usually get 14-15 mpg.

'Course I can't resist punching it a bit -- there is just so much power! The traffic to work on the loop was light given it was a holiday for some. I punched it when 2 additional lanes to the left opened up on a merge, and very quickly hit 112 mph, which even I know is too fast for the conditions. I reluctantly scaled back to 70 or so...

marc777

Try resetting the trip computer once the engine is warm - its easy to underestimate just how low the MPG can go on warm up. I do a 15 minute commute, with the first half of the trip its real bad, but if I reset, the second half of the trip gets sensible.

Marc

ValueplusClass

...One more thing... the gas mileage should improve through the break-in period.

Barney

Leslie, something definately sounds wrong. I'd say it could even be your trip computer but if you keep having to fill up the tank than it must be real. All of the things people have mentioned will have a MINOR effect on your mileage but the overall equation is very simple. Look at how much gas you use over what distance. Sitting at idle means you are using more gas but not going any distance, hence as you sit there you will see your mgp go down. People get better mileage than you do with a huge SUV AND a large engine. I can't comment directly on the E500 as I have an E320 (2003) but it averages about 23 with mixed driving and my lead foot and a 1 mile steep hill I climb at least once a day so I can't imagine the E500 would be getting only half the mpg as my car. On my 15 mile commute to work (downhill for the first mile) I often get 28 to 30 mpg and yes when I first start the number is much lower but gradually goes up as I drive. I have not noticed any change in mpg from when the car was new till now with 2500 miles.

Dema

BTW Does anybody know why engine from BMW 745 is less fuel hungry, although 745 weights 4376 lbs in opposite of 3815 lbs of E500? BMW claims 18/26 economy and the engine a bit more powerful. It will be nice if MB could make similar results. On my luck MB has good diesel engines, so I'm more curious, than worried.

LowTech

I don't know all the details, but Valvetronic and Double Vanos combine to add to economy without losing power.

It won some award for the technology...