Zavato

How accurate is the dash readout showing MPG? I went on a 130 mile trip yesterday and my car is telling me I got 29 MPG.

This from an 2012 E350. If it's true, that is better mileage than I get on my 2009 V6 Accord (I can count on 27 MPG on the highway from my Accord)

thefisch

The readout in my 2011 E550 is always .5-1 mpg too generous compared to manual calc at fill up. It has never been under what I calculated. Even with that margin, that's still pretty good mileage. I get about 26mpg highway with the NAV8.

thenew3

Similar to thefisch, over 20k miles I've found the on board computer to be about 0.5 to 1 mpg too optimistic. That is, if it says 29 MPG, it's likely 28 to 28.5MPG. Still not bad for such a heavy car.

Best I've ever gotten on my E350 wagon was 31 mpg going 65mph on a 400 mile trip.

We plan to take it on a 2500 mile trip this summer, hoping to average close to 30, although with a full load of people and luggage as well as a roof cargo box, and lots of stops to see the sights, we may not get anywhere near 30.

Johnny Rad

My car is consistently 1mpg optimistic.

looney100

I tracked mileage in our E250 for a few months. Computer was pretty consistent at understating consumption by 6%.

blegthbloo

Agreed on ~1mpg optimistic. The best I've gotten in my 2013 550 is 32.1mpg (on the readout), and the best I had on my 2011 350 was 28mpg all highway for an entire tank. The best I get on my 2012 R1 is about 29 (lol...)

Overall very impressed with the V8 TT

El Cid

My car is about 1 MPG pessimistic based on my testing in the past. One problem is that when it resets, it starts at about 22 MPG even if you are going down hill with foot off the accelerator. So it takes quite a few miles for it to truly reflect mileage.
My best was 34 on interstate at 65 MPH using cruise. Using cruise control will increase your mileage.

thefisch

Funny, after reset mine always starts out with 19 mpg.

LSkrabut

on my 2014 E250 (diesel), I been tracking the mileage and since day one on a spreadsheet.


57300K miles
40.73 Ave MPG via math
43.2 Ave MPG per computer totals.

VegasE

It's been the case with every car I've owned the past 15 years. It is so prevalent that I've seen articles about it in some auto mags. There are some hacks so you can correct it but not worth the bother to me.

Sunnyslope48

What is it about calculating mileage that the car does incorrectly? Measure miles, measure fuel, or calculation? And how do you know which is incorrect?

Zavato

So today on a 65 mile highway ride, traveling roughly 65 mph, my readout at the end of the trip told me my mpg was 32.2

I just don't believe it is possible out of a 302 hp awd sedan that weighs 2 tons.

Sunnyslope48

Eisenhower Tunnel to Denver. Definitely could be 30+. But, I'll bet that's not where you were driving.

Zavato

Good call- I was in upstate NY

Raymond Lee

My previous car 2012 E350 Bluetek was about 10% off but with 2014 e250, it is pretty accurate. Pretty pleased about it.

El Cid

Were you using cruise control? Surprising about how much this increases MPG. As posted above, I have gotten as much as 34 MPG at same speed on interstate.

Zavato

Mostly using cruise control-

BlankProc

So far I'm pretty happy with the mileage on my RWD E350.

Coming out of a C250 the mileage on that four banger was incredible. I was in mid thirties on long highway trips. But, that was a C and this is an E.

I'd be surprised to achieve that in the E350, which seems to fall somewhere between a gas sipper and a guzzler. I commute on back roads mostly to work and the MPG isn't too hot, probably low 20s.

669cpb

My E350 Bluetech 2013 is averaging about 43mpg according to the car and about 38MPG with the math.

Tump43

I mainly do the same back road commuting you do but, with a lot of hills. I average 18.5 mpg in my 2014 E350 if I drive very conscientiously. Don't know if any thing is wrong with my car. The MB literature has led me to believe that my car should get at least 21 mpg on the back roads. Any ideas as to the cause? I keep my tires at 33 psi cold, use premium gas, have 20k miles, new oil (Mobile1 0W40), oil filter (OE), air filter(K&N), cabin filter (OE) and brake fluid (Pentosin), but not wiper blades.

Zavato

Your tire pressure is a little low. Hills kill mileage though-