1998 E300 low mpg

[JCommiss]

Hey all,

I've been tracking my mpg over the past three tanks of gas and found it was only 28 on the highways at 75mph. I've heard so many people talking about at least 30+ with this vehicle, even higher in some instances.

The air filter, oil filter, and fuel filters are all new. I called a local diesel shop and was told if the injectors were the causation the engine would idle roughly, or there would be some sort of smoke kicked out the exhaust (which it does SOMETIMES going down hills while accelerating on the highway). He recommended that the Mass Airflow Sensor may be bad. I've read if the MAF is bad you will easily know, as it will trip a CEL and the car won't function properly - not just a reduction in mpg.

Thanks for all your help, and if you guys want any further information I'll supply!

[RunningTooHot]

I've yet to go through a full tank in my "new" '98, but I'm think I'm not getting as good of mileage as I did in my '95 NA w124 OM606. Could it be that the fuel gauge isn't calibrated as well in the w210? I'll find out when I fill the tank.

More likely is that I can't seem to keep my foot out of it. I HAD to keep my foot in it with the '95, but the '98 makes more power - and I am weak & yield to temptation. More power made = more fuel used. (Maybe once the 'newness' factor wears off I'll do better?)

Originally Posted by JCommiss

...or there would be some sort of smoke kicked out the exhaust (which it does SOMETIMES going down hills while accelerating on the highway).

No offense intended whatsoever, and I am actually being a hypocrite, but what you stated there may have something to do with it. Accelerating while going downhill? You're definitely not using "hyper-mileing" techniques.

[tjts1]

Your car is rated 23 city, 31 highway, 26 combined. The highway portion of the test is done at UP TO 60mph.
Fuel Economy of the 1998 Mercedes-Benz E300 Turbodiesel

3 cars from same model year averaged 27.5mpg over 38,000 miles.
1998 Mercedes-Benz E300 MPG Reports | Fuelly
I don't see anything wrong with your 28mpg at 75mph.

[Skid Row Joe]

Although the highs and lows of that car model is a lot higher and lower, the '98 E300TD's window sticker from Mercedes-Benz was EPA rated @ 26 City / 36 Highway.


The:
28 mpg @ 75 mpg is stunning, for the dead of winter in Colo for that car, considering that all the calculation was likely not all @ 75 mph.

[shertex]

Originally Posted by Skid Row Joe

Although the highs and lows of that car model is a lot higher and lower, the '98 E300TD's window sticker from Mercedes-Benz was EPA rated @ 26 City / 36 Highway.


The:
28 mpg @ 75 mpg is stunning, for the dead of winter in Colo for that car, considering that all the calculation was likely not all @ 75 mph.

I believe he EPA highway figure is 31.... That window sticker figure sounds inflated.

[Skid Row Joe]

Originally Posted by shertex

I believe he EPA highway figure is 31.... That window sticker figure sounds inflated.

I'm looking @ my old 99 E300TD's window sticker. 26 City / 36 Highway. The '98 E300TD was an identical engine car. It wasn't "31," on a 98, since the 96/97 E300's non-turbo window sticker was; 25 City 35 Highway.

[RunningTooHot]

tjts1:
Yes, you are correct. And I was not aware of the 60mph highway speed used on the tests. That's ridiculous.

The "corrected" mileage vs. the original mileage estimates are interesting however. I'm not sure what formula they utilized to "correct" the original ratings, or how the correction factor affects a diesel vs. gas engined car.

Also, I would postulate that people whom track their mileage on Fuely.com probably would tend to be a bit more focused on efficient driving, thus their interest in Fuely. So if the Fuely drivers are getting 27.5 on average.... well, the lead-foots may not do so well.

[TMAllison]

Are you running the correct size tires? Inflation correct?

Little things like coasting up to stopped traffic or red lights rather than charging forward and braking at the last second, and constantly activating the turbo accelerating from a stop can make a difference in mpg's.

[GregMN]

Originally Posted by JCommiss

I've heard so many people talking about at least 30+ with this vehicle, even higher in some instances.

Did you buy your car off e-Bay or Craig's list ? Cars sold there get up to 50mpg.

1: It's winter. You're burning winter fuel. = < mpg
2: It's winter. Higher mechanical resistance in cold weather. = < mpg
3: You are driving too fast. The mpg difference between 65 and 75 is a lot. Spend $60 on an Ultra-gauge : UltraGauge OBDII Scan tool & Information Center
4: Inflate your tires.
5: Wipe that silly grin off your face and get your foot out of the throttle.

Or, for the extra $3.899 / fill-up, just drive it the way that makes you happy. That's cheap happiness.

[KarTek]

My '98 gets 28MPG combined and low 30's on long highway trips. I peaked at 37 once but most times it's around 34. This isn't just a random sample, I check every tank on trips and most times daily driving.

[uberwgn]

Originally Posted by JCommiss

I've been tracking my mpg over the past three tanks of gas and found it was only 28 on the highways at 75mph.

J, welcome aboard! I hope you aren't filling the car with gasoline...that might be an issue. OTOH, running thru the Rocky Mtns at 75mph and achieving 28mpg sounds pretty darned good to me

Our 1998 diesel is lucky to hit 31mpg traveling on level terrain at 70mph or less. And that's during the warm months.

We've had two of these W210 turbodiesels. They both achieved the same fuel economy when operated under similar conditions. No surprises there.

[Quahog]

former 99 E300 owner checking in:

your mpgs seem normal for the conditions.

to improve them, you'd have to drive like an old man w/hat and that's no fun

let the engine oil come up to temp, then flog it & grin

[jay_bob]

I have been averaging 26-28 mpg in my W210 over the course of last year.

I don't drive like grandpa but I don't drive it like I stole it either.

[shertex]

28 mpg on winter diesel is about what I get....though I can see 30-31.

[ROLLGUY]

When I had my '98 the best I got was 31, but the average was around 26 running biofuel. My friend has the exact same car and we drove it down to Mexico last month. From the Hesperia to Mexicali (downhill most of the way) we got 39.7 MPG (filled it to the brim on level ground both times). Of course we had to do the math from liters to gallons (Smartphone app). I would not expect to get much more than 29ish with combined city/highway driving above 65 MPH.