rumordude

I recently drove from Seattle down to Los Angeles (and back), and spent a bit of time playing around to try to get the very highest fuel economy with a bunch of different metrics. Of course this was all strictly unscientific (i.e. I didnt check air pressure, and the temperatures changed quite a bit, as did the road itself ad naseum). But, since i usually get about 15 MPG, I thought it'd be a nice experiment.

The basic breakdown with some playing was this:
Over a decent stretch of I5 I was able to get this up (and over) 25 MPG for quite some time (at least half an hour) With some clever drafting (tailgating) and very smooth, manual throttle with as little turning as possible. It seems the best fuel economy comes around the 65ish MPH. As you go faster it seems to peel off, and around 75-80 MPH it peels off hard back towards that 15 MPG. Interestingly, if you go slower (say, 55 MPH), your fuel economy worsens also -- you are burning less gas, but you're burning it for longer to get the same distance!

Here's a fun camera-phone photo partway through the experiment:

BoBcanada

Thats not bad at all!

ldangeli

Yeah I found that if I keep it at 77 and under, it ranges from 17.x to 21.x

Newzchspy

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Same with my ML55, If I run below 75, it'll jump to low 20s, high teens. Above that I am just pushing air like a brick!! The reason why it does real well above 55 MPH to about 75 MPH is engine efficiency. Above 75 MPH, you're just pushing a whole lot of air on both the 55 and the 63.

bartdude

to be honest the gas mpg is horrible!! its just tempting to drive econimcally!!

Jo

25 mpg that is pretty good. Who needs a smart car when you get 9.4l per 100km?

ldangeli

You don't buy an ML63 or any other AMG for gas mileage. If you want good gas mileage, buy a hybrid.