My fuel mileage to the tank can't be right... - Page 2 - PeachParts Mercedes-Benz Forum

Bio300TDTdriver · #16 01-02-2008, 12:55 PM

Quote:

Originally Posted by vstech

that chart is interesting, but the OP is driving a 124, with a MUCH more efficient rear gear ratio and 6 cyl engine with MUCH more power and better fuel economy.
the 123 N/A vehicles had as high as 3.69 rear ratio, where the 124's with their clean 603 turbo motor and low 2.66 or so rear gear ratio get around 25 city and 35 highway. even at 80MPH...

I was with you right up until you said 35 mpg highway. I have the wagon not the sedan. The old EPA numbers were 23 city, 27 highway. The new numbers (they re-did the calculations to reflect real world driving) 21-25.

The sedan was 25 city and 29 highway old and 22 city and 27 highway new. Based on my fuel economy, you would need to be going down hill, with a tail wind at 55 mph to come close to 35 mpg. There is no way you will get 35 mpg at 80 mph. Only the cars sold on EBay get 35 mpg highway.

Magoo · #17 01-02-2008, 01:29 PM

Quote:

Originally Posted by Hatterasguy

First you need to figure out your mileage. 280 miles to a tank means nothing, what does a W124 hold 21 gallons? Did you run it dry? Did you run it until a 1/4 is left? Chances are the fuel guage is off.

Next check the odometer with a GPS, its probably slow.

I was thinking the same thing.
While the Odometer may end up being the culprit, you need to figure out Miles driven per gallons of fuel you put in first.
I thought my mileage was low initially until I figured out that my gauge reads empty when there is still 4 or 5 gallons in the tank.

vstech · #18 01-02-2008, 02:02 PM

Quote:

Originally Posted by Bio300TDTdriver

I was with you right up until you said 35 mpg highway. I have the wagon not the sedan. The old EPA numbers were 23 city, 27 highway. The new numbers (they re-did the calculations to reflect real world driving) 21-25.

The sedan was 25 city and 29 highway old and 22 city and 27 highway new. Based on my fuel economy, you would need to be going down hill, with a tail wind at 55 mph to come close to 35 mpg. There is no way you will get 35 mpg at 80 mph. Only the cars sold on EBay get 35 mpg highway.

ok, maybe 35 is streching it a bit... but on level highway, around 60mph, I bet you could get 35mpg...
OTOH, my point was that the chart is not very effective for the 124 vehicles...

Bio300TDTdriver · #19 01-02-2008, 02:11 PM

Quote:

Originally Posted by vstech

ok, maybe 35 is streching it a bit... but on level highway, around 60mph, I bet you could get 35mpg...
OTOH, my point was that the chart is not very effective for the 124 vehicles...

Your point was correct about everything else. The 124 (.31Cd) is 27% more aerodynamic than the 123.

Douglas.Sherida · #20 01-02-2008, 02:28 PM

John,

I agree that the chart data is not directly pertinent to the OP's question.

I know he was referring to a 124 (and a sedan at that), while the chart data referred to a w123 wagon. I only posted the chart data as a discussion point.

Here's the thing: even if the 124 is 27% more aerodynamic (where did that number come from anyway?) the decrease in fuel economy from 56 to 75 mph could still easily be as much as 20%.

Bio300TDTdriver · #21 01-02-2008, 02:34 PM

Quote:

Originally Posted by Douglas.Sherida

John,

I agree that the chart data is not directly pertinent to the OP's question.

I know he was referring to a 124 (and a sedan at that), while the chart data referred to a w123 wagon. I only posted the chart data as a discussion point.

Here's the thing: even if the 124 is 27% more aerodynamic (where did that number come from anyway?) the decrease in fuel economy from 56 to 75 mph could still easily be as much as 20%.

Whoops I didn't site the source. Mercedes-Benz E Class Owner's Bible

Bio300TDTdriver · #22 01-02-2008, 02:36 PM

Quote:

Originally Posted by Bio300TDTdriver

Whoops I didn't site the source. Mercedes-Benz E Class Owner's Bible

Edmunds agrees with you. The test was from 65-75. I can't find one from 55-75 because they probably did get run off the road.

Test #2 Lower Speeds Saves Gas

Result: Substantial savings on a long trip

Cold Hard Facts: Up to 14 percent savings, average savings of 12 percent

Recommendation: Drive the speed limit.

Remember a thing called the speed limit? On most highways it is either 65 or 70 mph. How fast are the cars and trucks around you going? From 75 mph to 90 mph. These people are wasting a lot of gas for the chance to get there a little earlier. Factor in safety concerns and a speeding ticket once or twice a year and going fast is a costly proposition.

Method: This test was simple. For 50 miles we drove with the cruise control set at 65 mph. Then, for another 50-mile stretch we drove with cruise set at 75 mph. We repeated this test going in the opposite direction. It is amazing how obvious the difference in gas mileage was. Just think what would have happened if we had slowed down to 60 mph. The only problem is with impatient drivers behind you. One driver became so irate that he tried to run our editor off the road. Still, if you are pinched by gas prices. Leave a little early and drive the speed limit (in the slow lane).

DslBnz · #23 01-02-2008, 03:33 PM

Quote:

Originally Posted by Bio300TDTdriver

I was with you right up until you said 35 mpg highway. I have the wagon not the sedan. The old EPA numbers were 23 city, 27 highway. The new numbers (they re-did the calculations to reflect real world driving) 21-25.

The sedan was 25 city and 29 highway old and 22 city and 27 highway new. Based on my fuel economy, you would need to be going down hill, with a tail wind at 55 mph to come close to 35 mpg. There is no way you will get 35 mpg at 80 mph. Only the cars sold on EBay get 35 mpg highway.

Those EPA numbers were with the trap in place. Mileage significantly went up when the trap was replaced with the oxidation catalyst.

For instance, an '87 300SDL was rated at 22/23 mpg. The previous year's federal model had ratings of 25/27 mpg. Thus, I would assume, the 300D/TD should be proportionately higher as well.

estod · #24 01-02-2008, 04:00 PM

Easy --

Many people don't really know what kind of mileage they're getting, because they are not careful about refueling. If you will buy from the same pump at the same station, trying to place the car exactly the same ... and take the nozzle out when it clicks off, instead of burping the tank -- you will come close to real mileage figures.

Another easy check (air & fuel filters & tire pressures first) is whether or not you have a sticking brake -- jack up each corner & spin the tire. A slightly sticking brake caliper will have a big effect on mileage.

Since diesels run unthrottled & therefore suck down a lot of air, I bet your dirty air filter is good for 2 mpg, for starters.

Let us know how it goes.

Magoo · #25 01-02-2008, 04:10 PM

Quote:

Originally Posted by Bio300TDTdriver

Edmunds agrees with you. The test was from 65-75. I can't find one from 55-75 because they probably did get run off the road.

Test #2 Lower Speeds Saves Gas

Result: Substantial savings on a long trip

Cold Hard Facts: Up to 14 percent savings, average savings of 12 percent

Recommendation: Drive the speed limit.

Remember a thing called the speed limit? On most highways it is either 65 or 70 mph. How fast are the cars and trucks around you going? From 75 mph to 90 mph. These people are wasting a lot of gas for the chance to get there a little earlier. Factor in safety concerns and a speeding ticket once or twice a year and going fast is a costly proposition.

Method: This test was simple. For 50 miles we drove with the cruise control set at 65 mph. Then, for another 50-mile stretch we drove with cruise set at 75 mph. We repeated this test going in the opposite direction. It is amazing how obvious the difference in gas mileage was. Just think what would have happened if we had slowed down to 60 mph. The only problem is with impatient drivers behind you. One driver became so irate that he tried to run our editor off the road. Still, if you are pinched by gas prices. Leave a little early and drive the speed limit (in the slow lane).

Time saved on the 50 miles by going 10 or 15 mph faster is negligible as well- only minutes.

vstech · #26 01-02-2008, 08:42 PM

Quote:

Originally Posted by Magoo

Time saved on the 50 miles by going 10 or 15 mph faster is negligible as well- only minutes.

your life can be measured in minutes... however, a 50 mile trip with a 15mph increase will only net you 10 to 15 minutes, IF nothing else obstructs your commute. brian carlton said it best, if you are saving more than 3 minutes it was luck, not speed that did it.