96 E300 Fuel Economy - PeachParts Mercedes-Benz Forum

DieselJim · #1 04-25-2014, 09:04 AM

Well my new to me 96 seems to be getting right at 30 MPG. This is a little lower then I expected but not bad. I am opening her up a bit on the freeway when traffic is light but usually battle 15-30 miles of stop and go traffic daily on my 40 mile each way commute.

What should my expected fuel economy be for these kind of driving conditions? I felt like I got about 32-34 when my 92 300D was at its best(some times I calculate about 35 for a tank) but always well over 30 unless I was sitting on the freeway idling for 14 hours.

GregMN · #2 04-25-2014, 09:18 AM

Expect what you are getting.
All freeway driving about 32.

tjts1 · #3 04-25-2014, 10:40 AM

The W210 is heavier than the W124 with the same 0.29 drag coefficient BUT larger frontal area so slightly higher fuel consumption is to be expected. My 97 (722.6) has returned a high of 33mpg (all highway) and a low of of 27mpg (mixed driving) in the 2000 miles since I bought it. I'm happy with that.

Jeremy5848 · #4 04-25-2014, 01:06 PM

The first W124 diesel, the 1987 300D Turbo, had a CD of 0.32. By 1995 the E300D had been slightly improved, to 0.31. The W210 1996 E300D improved that to 0.29.

[Showing the difficulty of pushing CD ever lower, even the 2014 Tesla Model S has a CD of 0.24. Not much improvement over 20 years.]

The "curb weight" of the 1987 300D Turbo is 3375, the 1995 E300D is 3485, and the 1996 E300D is 3538. The spread across the 3 models is 163 pounds, a trivial amount (less than 5%).

These numbers are all from factory brochures issued at the time the cars were being sold by dealers. YMMV.

On a personal level, our 1996 E300D' fuel economy has averaged 27.1 MPG since we purchased it in late 2007 (accumulated miles 46,000; total on car 294,400 as of this writing). Much of the driving has been around-town. Constant freeway driving gives 30-32 MPG. It is my wife's DD and since we bought the '95 has never been out of the San Francisco Bay Area (~5,000 miles/year).

The 1995 E300D is newer to us, having been purchased only two years ago and has 212,000 miles on the clock. Its average fuel economy is 28.0 MPG over 22,000 miles. It is my DD and we use it for trips so that it accumulates more miles (~10,000/year) than the '96. Our last road trip averaged 31 MPG at 75-80 MPH (I-80 across Nevada-Utah) on winter diesel. At sea level on summer diesel and 65 MPH both cars would do much better (we'll probably never find out).

Why the '95 does better than the '96 I do not know. The engines are nearly identical (OM 606.910 and .912); perhaps the '96 is simply showing its age. Both cars use the same B20 biodiesel blend from the same pump at the same station; road trips are typically on D2 since biodiesel is harder to find.

Jeremy

GregMN · #5 04-25-2014, 01:26 PM

Quote:

Originally Posted by Jeremy5848

Why the '95 does better than the '96 I do not know.

I do:

1996 W210 Axel ratio 3.46
1995 W124 Axel ratio 2.87

Chris W. · #6 04-25-2014, 01:36 PM

I'm fortunate that my '95 does a bit better, 32-33 during winter, and 34-36 during summer. I track every tank and pretty much drive the same route in my commute, which is 110 miles round trip. Out of that 110 miles, I'd say about 12 miles is in town with stoplights. A few in town errands on weekends.

I think that larger tires on the 210 may contribute to lower mileage as well. Perhaps more rolling resistance. Just an opinion, no facts behind it.

Rgds,
Chris W.
'95 E300D, 417K

VW1300 · #7 04-25-2014, 02:19 PM

To OP: I'd say averaging 30 in a mix of driving seems about right. Since I fixed my EGR issue, I've been getting about that. Highway miles returns about 33 or so.

Skid Row Joe · #8 04-25-2014, 02:53 PM

You're very fortunate./ If your car will always achieve "30 mpg," it'll be the only one I've ever heard of that does that well. Mid-20s (less than 30 mpg) are the norm for that car in mixed-use - and low 20s/high teens for all/most off-highway use.

Jeremy5848 · #9 04-25-2014, 03:41 PM

Greg, my factory literature gives 2.87 for both the 1995 and 1996 E300s. I confirm that by comparing RPM/MPH in the two cars. What is your source?

BTW, the 1987 300D Turbo has a 2.65 differential but it also has the more powerful OM603 engine.

Jeremy

Quote:

Originally Posted by GregMN

I do:

1996 W210 Axel ratio 3.46
1995 W124 Axel ratio 2.87

Jeremy5848 · #10 04-25-2014, 03:54 PM

The 15" wheels of the W124 carry /65 tires while the 16" wheels on the W210 have /55 tires. The outside diameter is within 0.5%. W210 typically has slightly wider tires but I doubt the effect is significant.

BTW, my '95 has 16" W210 wheels with 205/55 tires, identical to what I run on the '96 (so I can interchange). The factory spec for late W124 is 195/65-15 but I bet most owners have been upsold by tire stores. The W210 is spec'd at 215/55-16.

Personal driving style and road conditions / type of driving are likely the big factors in fuel economy.

Jeremy

Quote:

Originally Posted by Chris W.

I think that larger tires on the 210 may contribute to lower mileage as well. Perhaps more rolling resistance. Just an opinion, no facts behind it.

Rgds,
Chris W.
'95 E300D, 417K

tjts1 · #11 04-25-2014, 04:50 PM

Everyone seems to ignore frontal area. Park the 2 cars side by side and look at them from the front. The 210 makes a much bigger hole through the air than the 124. Drag coefficient only tells you how aerodynamic the shape is. A scale model of 124 has the same drag coefficient as the full size car.

Total aerodynamic drag = dag coefficient X frontal area.

GregMN · #12 04-25-2014, 06:05 PM

Quote:

Originally Posted by Jeremy5848

Greg, my factory literature gives 2.87 for both the 1995 and 1996 E300s. I confirm that by comparing RPM/MPH in the two cars. What is your source?

I was using a spreadsheet of MB diesel car specs. It is apparently wrong for the '96 model. I looked it up on EPC and the 3.46 started in '97 with the 5 speed trans.

Jeremy5848 · #13 04-25-2014, 06:50 PM

Quote:

Originally Posted by GregMN

I was using a spreadsheet of MB diesel car specs. It is apparently wrong for the '96 model. I looked it up on EPC and the 3.46 started in '97 with the 5 speed trans.

Thanks for catching the error, Greg. There were a lot of changes in 1996-97 and apparently even the factory didn't keep (or release to dealers or owners) all the details.

Jeremy

DieselJim · #14 04-26-2014, 01:41 PM

Excellent info. I just wanted to know what to expect and to see if what I was getting was typical or there was a problem to debug. The aerodynamics thing makes sense. Also the engine is probably not as efficient as a turbo 2.5

Jeremy5848 · #15 04-26-2014, 09:31 PM

The 4-valve 606 head probably breathes better than the 2-valve 602 but the turbo may more than compensate. Obviously combining the two (as in 606 Turbo) is even better.

Jeremy

Quote:

Originally Posted by DieselJim

Excellent info. I just wanted to know what to expect and to see if what I was getting was typical or there was a problem to debug. The aerodynamics thing makes sense. Also the engine is probably not as efficient as a turbo 2.5