What speed gives the highest mpg?
MBWorld Fanatic!
Joined: Nov 2009
Posts: 2,616
Likes: 160
From: Southeastern USA
2010 E350 Luxury Sedan, Engine 272 (V6)
I tested my onboard computer when I first got my car and then a couple of times since. It either reads about 1 MPG lower or the same as when I use the fill tank and check odometer method. Used same pump at same station for the testing.
Super Member
Joined: Oct 2010
Posts: 764
Likes: 10
From: North Carolina
2010 E350, 2015 S550
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
