Good idea. I'm willing to try this for 1 or 2 days, but I can't drive without any nice acceleration for a whole week I'll let you know what I find. By the way, I have a G35x (to which I added the paddle shifters), so my fuel economy will be a little worse than those driving the G35s or the regular G35. Still, I can compare D with light driving and M with light driving and let you know. I did a run in D with cruise control on the freeway today driving 65mph and averaged 27mpg for that run (about 12 miles on a reasonably straight run with no uphills or downhills). Doing the same on the way back at 55mph, I averaged 29mpg for the first minute or two, but then it started pouring, and everyone slowed to 40mph, so I couldn't continue the test. 27mpg is by far the best mpg I've ever gotten (while looking at it).

I also discovered the the Info/Fuel Economy mpg average, is the 'lifetime' average until you reset it. So it does not follow the trip A, trip B averages. When you reset those, they don't affect this one. Apparently in my first year of ownership, I've averaged about 15mpg Admittedly though I really 'enjoy' this car if you know what I mean, so I'm not that surprised. I have also done mostly city driving, and a lot of DC rush hour highway driving.

Cheers
Tamir

 

I ended up having the opportunity to drive the same stretch of highway twice later in the day. My first try, I now stayed at 55mph on cruise control, and got 31mpg. For my second try, I stuck to 75mph and got 21mpg. So:

55mph = 31mpg
65mph = 27mpg
75mph = 21mpg

Pretty significant difference between 55 and 75. Course if I drove 55 down that highway every time I drove it, I'd go nuts. But anyway, it was an interesting learning experience.

Cheers
Tamir

 

I've had similar results (although at 75, I still get over 24 mpg).

This is exactly why we need a double overdrive 6th gear. 5th gear is perfect for 55mph, but way to steep for highway cruising. With as much torque this engine has, we don't need to cruise at 3k on the highway.

I can't imagine how terrible the fuel economy would be if this car wasn't so aerodynamic!

Things could be worse though, we could be getting single digit fuel economy, even with a 7 speed auto, like the C63 AMG.

 

D


for me.

 

M1/2/3 for you...

4/5 don't exist. Except when you're going 100+

 

Ok, so I tried driving conservatively for a full tank using just D and managed 23 MPG for about 60/40 highway/city driving. In M mode, I couldn't come anywhere near this - was at about 19mpg when I gave up and started driving the way I normally drive again (a lot more fun) and am averaging just under 17mpg now by using D when going through slower areas like strip malls and M the rest of the time. Mike, you're right that it's not easy to get better mileage using M than using D - if at all possible.

Cheers
Tamir