otakki

Did a search but couldn't find any info. My car doesn't have the mpg bar graph so I'm turning to you folks. Conventional info usually states optimal speed between 55-60mph. However, W212 has a very low Cd of 0.26 so I wonder if the number would be different. Thus I'm interested in seeing if anyone has tested various cruising speed to see the mpg graph result.

My question is: What W212 speed gives the highest mpg on the mpg bar graph? Of course, that's assuming nearly flat terrain with minimal head or tail wind.

Thanks.

BenzV12

I mostly use other things in the dash but here is what I come up with . From my driving experience, 80 km/h - 55 mph and RPM is 1500 and I see as low as 3lt/ 100 km
I contribute this to having 7 speed wonderful tranny and massive torque to the car

CEB

It is well versed that the the optimal speed for fuel efficiency is between 55 and 60mph.

ghstudio

I wonder what the sweet spot is for speed on the diesels?

CEB

You can try it out yourself by doing a couple of runs of about an hour each on a low traffic highway. Diesel up and hit the highway. Set your cruise at 55. At the end of the run, fill up again and manually calculate the mileage. Drive back setting the cruise for 65 and re-check your results.

hx_guy

I would think that the lower the speed, the better your MPG as wind resistance will be lower.

Obviously you have to keep up with traffic, so if the speed limit is 55 MPH, then go 55 MPH but from a fuel economy point of view, you'd most likely get better fuel economy at 50 or 45.

otakki

The maximum mpg takes into consideration both internal friction at low speed and wind resistance at high speed. Above 30mph, wind resistance increases rapidly with speed. Thus, striking the balance between these two is the key. Some recent studies actually showed higher efficiency at higher speed compared to studies from before. In most cases, greater efficiency is achieved with 65mph when compared to 45mph. So 45mph is definitely no good.

El Cid

Go to fueleconomy.gov. (Googled most efficent speeds) May be from the government, but probably as accurate as anyone. Agree that 50 is probably optimal. While we may like to think an M-B can go faster and be more economical, I doubt it.
They do have some other tips on the site, but the one I really have proven is using cruise control. it also helps prevent speeding tickets.

ImInPA

47.6 mph, assuming you are at sea level, 73 degrees F, 45% humidity, and 91 octane fuel. I just love making this stuff up.

El Cid

[QUOTE=otakki;5318122]
My question is: What W212 speed gives the highest mpg on the mpg bar graph? Of course, that's assuming nearly flat terrain with minimal head or tail wind.

The bar graph on my 2010 maxs out at 40 MPG, does yours? Also noted that when I reset the other MPG gauges, they start at about 22 MPG no matter if I am going down hill with foot off accelerator. My previous cars with MPG gauges would show 99 MPG going downhill with foot off accelerator.
BTW, my best MPG is to leave it in the garage and drive my wife's 4 cylinder RAV4.

SolidGranite

Way too many variables to nail down an exact speed. You have coefficient of drag, terrain, temp, humidity, trans, engine power, weight, fuel type, tires, tire pressure, wind speed and wind direction to name a few.

Green E-300 DT

For posting your Fuelly.

I think that you will (and have already) discovered that you do better
fuel economy wise when going faster than 45 or 50 mph.

If I had your approximately higher by ten (10) percent gearing in mine, I think my 'sweet-spot'
would be at 65 mph instead of 60 mph where it seems to be now.
At a true 60 mph, mine turns exactly 1772 rpms. What's yours?
My max. torque is supposed to be between 1800 and 2400 rpms.



DHG

El Cid

Per various testing organizations, optimum speed for cars is 50-55 MPH.

Arrie

It is the lowest speed you can drive with the highest gear with engine running properly. This would be engine speed somewhere around 1000 rpm. This would probably be somewhere around 40 - 45 mph.

samkimg

Is it really MPG (Miles per Gallon) we should be tracking or SPM (Smiles per Mile)? Seriously, the smiles I get when driving my MB are worth much more than a higher MPG ... if I cared about MPG as much I'd be driving something much smaller, slower and less "fun".

On getting better mileage, over the past 43000 miles, I've been getting 20-27 MPG, the lower in all-city driving and the higher on long, high-speed (80 MPH on cruise) runs to Disneyland. On average I get ~22.8 MPG all around with my E350 in [C] mode and using cruise whenever I can.

Oh, and Rock 'n Roll music makes me drive faster, but funner ... anyone else's music have an affect on their gas pedal usage?

BM2BZ

agree ! i could care less about mpg...unless i have to drive more than 100 miles/day .

as for music, music really affects the way i drive. hip hop makes me drive a bit more aggressive . jazz/blue, in a more relax way .

Nuru

seems like 65 - 70 mph for me, as long as I keep steady at that speed. Any hills,and the the mpg dips a mile or two.

ImInPA

Keep in mind with the Bluetec, you can have your cake and eat it too with regards to mpg. No need in anyone "roughing it" just for extra mpg.

Green E-300 DT

The newer Bluetec Diesels do not do as well Fuel Economy wise as the older model diesels.

The differences in the E-350 gasser and the diesel EPA ratings is only one (1) mpg!

But that's progress I guess. Blame it on the tougher smog laws and the heavier E-Class sedans.

One wonders how the S-Class diesel sedans get the same EPA ratings as
the E-Class diesel sedans and the S-Class is all wheel drive to boot.
Something is fishy! I do not believe that they do.



DHG

ImInPA

The EPA sucks at generating acurate numbers for Diesels. Every diesel I have owned in the US has exceeded the EPA ratings. I have a neighbor with the E320 CDI. Comapring notes, I do a bit better on the highway with my Bluetec, he does a bit better in the city. I believe most of the differences are due to taller gearing on the Bluetec to improve highway miles and the increased weight of the W212. Also, the EPA scoring is different today than when the E320 CDIs were out. ALL vehicles to a "hit" to their EPA figures due to new, supposedly more realistic, testing.There is no real valid argument to be made relying on EPA figures alone.

Green E-300 DT

All you need to do is to view the results on Fuelly for the W-212 diesels.

They do not an can not get the fuel economy the 2005-2006 W-211 CDIs achieve.

Why? Mainly because the W-212s are not only at least three hundred pounds heavier
but they are wider also and have larger and heavier wheels with run-flats.
Also, because they are heavier, the engineers saw fit to gear them lower which means
they rev higher at any given speed in spite of their seven speed transmission.



DHG

El Cid

The EPA does NOT test all vehicles for efficiency. Much of the data on the window stickers is provided by the manufacturer to EPA. Also, EPA is more accurate than used to be on ones they do test, but still not real world. Consumer Reports probably has most accurate results, but based on their particular test site at the time of testing. Also, CR frequently fails to state that the car they tested was four-five years ago.
MPG figures are good for comparing one model to another or to other makes, but not for determining what you are going to get. In effect, a car rated at 40 MPG should get 5 MPG over one rated at 35 MPG, depending upon how you drive, how much junk is in your trunk, etc.

Green E-300 DT

My older CDI was rated (when new) by the EPA at 27 mpg city and 37 mpg highway.
The newer revised' EPA rating for the CDIs is lower at 25 city and 35 highway.

I can and do regularly get tank mileages better than the newer 'revised' ratings.
These tank mileage average figures include some city as well as mostly highway driving usually
over a period of several days with many cold starts and usually include a lot of A/C useage.
We like to ride 'in comfort' don't you know!

All you need to do is go to my Fuelly postings and see for yourselves.

I say again, these newer V6 3.0L Bluetecs, even though their engines are smaller and these later
cars do have the advantage of their seven speed transmissions, do not and will not get the fuel
economy that the older (on this continent) 2005-2006 CDI 3.222L diesels can and do achieve!

To prove my point, read my Fuelly and study what the newer model owners are reporting.
It is all there in black and white by individual owners.



DHG

mnje350

Not an answer to your question. . . But on a recent 250 mile flat interstate trip with little traffic at average 70 MPH, I recorded 28.9 MPG. This as reported by the on board computer with AC running. Not a clue what the mileage would be at a something lower. I was impressed with high 20's for this car. Gasoline 2010 E350.

Green E-300 DT

While your onboard computer is somewhat better than a guess, that's about all it really is.

I find that mine will show as high as forty (40) miles per gallon for the entire tank, but when I use my calculator and divide
the miles driven by the gallons used to fill the tank up to the brim, the computer can be off by as much as five (5) MPG.

With my CDI, I have seen computer readings over several hundred miles on a long trip
as high as 43 mpg, but when I fill the tank, it will figure out to only 37 mpg.
That is how far off some onboard computers can be.

By the way . . . with the fuel economy I am getting regularly, I am not complaining!



DHG