Poor fuel mileage on 210

[Scott98]

I've been getting only 28 mpg in my 98 E300D on the highway doing the speed limit. My tires are properly inflated. I've probably gone through about 8 tanks of fuel since I bought the car and the mileage is always the same. I thought these things are supposed to get around 34 mpg. Any ideas??

Scott

[DieselAddict]

Is your maintenance up to date? Perhaps your injectors aren't spraying at their best. It could also be the winter diesel fuel. Is your EC button on? It should be otherwise you're running with the AC on. I get about 31 mpg on the highway.

[Scott98]

The previous owner (it's a one owner car) was fanatical when it came to maintenance. I don't think he ever did anything with the fuel injectors though.
I always have the climate control on automatic. I never pay attention to whether the EC is selected or not. That is something I will take a look at. I don't think we get winter fuel around here. I've never had that problem with my other Benz so I doubt that's causing it. Any other ideas?

Scott

[nhdoc]

28 is more or less normal for these, especially in the winter. EPA estimates for the '98s were 26/34 with a combined average of 30. I get 27-28 all the time in the winter, in the summer it creeps up to 30-31...34 is exceptional mileage, though not unheard of as I did get that in one tankful this past summer. The '99s did a little better on the highway than the '98s.

I considered having the IP timing checked as that can influence mileage, but the stealership wanted $300 to check it and even if it resulted in 10% better fuel economy it would take years to earn that back so I just live with 28-31 MPG.

The guy who sold me my car had in his ebay listing 37MPG, but when I challeneged him on it after I bought the car I never heard back from him

[Scott98]

The main reason I thought 28mpg was poor was that my '97 got around 34mpg and I heard the turbo models got slightly better mileage.

Scott

[superlite17]

28mpg on Winter diesel is not bad at all. I agree with nhdoc. When someone is way overoptimistic with either MPG's or comes on with the "million mile diesel" pitch I always take a half step back because it seems they are trying to market the car to someone a little different than me.
Paul
______
98 E300

[Scott98]

Why does winter diesel lower your fuel economy?

Scott

[Hatterasguy]

Considering that it is winter fuel season 28 isn't bad. How dirty is your air filter, or fuel filters. My friend noticed that his mileage will drop slightly as his fuel filters age, he keeps track of every tank. Don't ask me why but it seems to.

Also make sure the AC compressor isn't engaging, keep the climate control in EC mode.


You do have 135k on it, it wouldn't be a bad idea to pull the injectors and have them tested. One or two probably are not as good as they could be.

[nhdoc]

The only thing I will say is if the car runs well otherwise (smooth idle, nice smooth acceleration, plently of power and doesn't smoke excessively) then I would not start tinkering solely with it with the idea of improving MPGs.

Sure, change the filters if they haven't been done in a while but to start tinkering with the injectors or pump to try and see if you will get another couple of MPGs is probably just a waste of time or money if you pay a mechanic to do it. My car runs so well that I have now abandoned the idea of averaging more than 30 with it, especially in the winter. 28 is pretty darn good for a full sized sedan with the power these turbos have. If yours is like mine then come summer you'll see 30 or so and just drive and enjoy it.

[Hatterasguy]

Injectors take like 30 min to pull and only cost $10 each to test at local shop. We did my friends in an afternoon. One was bad at 149k miles and they only charged him a grand total of $70ish to test all 6 and rebuild the bad one.

It took a couple of days to get the nozzel to rebuild the bad one, but he didn't need the car anyway.

It depends how picky you are in my book spending a little time and $70 to know you have 6 perfect injectors is worth it. Heck I spent about $400 on the SDL's to get them just right. (long story)

The only downside to the 606 is you need a special socket, for the injectors. MB sells it for around $30.

[DieselAddict]

I agree with nhdoc that it's a waste to go into expensive maintenance and repairs just to try to raise the mileage by a couple MPG. I did my own injector inspection and yes you can pull them all within 30 minutes, but if you're as careful as I am it will take much much longer to put everything back. The injector holes are notorious for collecting dirt and sand and careful cleaning is required before you put the injectors back. A better way to start is doing a Diesel Purge which is very easy to do, but even that may not be necessary. First I'd try what's been recommended here so far. IP timing is something that normally doesn't need adjusting, unless someone already messed it up.

Scott98, winter diesel fuel is a lighter distillate of crude oil than summer diesel and it produces less energy when it burns. Thus more fuel needs to be injected to have the same performance, hence the lower fuel economy.

[wbuhrman]

Two more things to check:

1. There is a switch near the shifter labeled "W" and "S". Make sure it is in "S" (Summer).

2. When you put the car in "D" from park be sure the shifter is pushed to the right. To the left is 4th gear and not 5th, which would reduce your mileage on the highway (with a resultant increase in rpm).

You might also recheck your tire pressure. A good tire pressure gauge is worthwhile and I've notice with large temperature variations (hot one day, cold the next), that will affect tire pressure.

My '99 E300 gets 31-33 mpg for my commute, FWIW.

Enjoy the car.

[deltajetfixer]

Originally Posted by wbuhrman

Two more things to check:

1. There is a switch near the shifter labeled "W" and "S". Make sure it is in "S" (Summer).

I was under the impression that all this did was enable engagement of 1st gear?

[superlite17]

All the winter/summer switch does is allow or exclude 1st gear when moving from a dead stop. Can't see how this would affect freeway mileage.
Paul
_______
98 e300

[W140 S600]

The "W" mode on the tranny allows for 2nd gear starts from a dead stop. It also engages a lower ratio reverse gear and a less agressive shifting sequence all to reduce slippage in wintery conditions.