I recently traded a 2007 Chevy 3500 with the LMM diesel engine for a 2008 Ford F-350 with the 6.4L diesel engine.  The Chevy had often achieved l9mpg on lengthy trips with no towing load, and its 6-speed Allison transmission was a dream.  However, I was not comfortable with its interior and I couldn't get over its styling, particularly the massive and ugly chrome from bumper. I originally thought that time would heal my dislikes, but it didn't.

I knew when I started to get serious about buying the Ford that its mileage would not be as good and the Chevy and that its 5-speed tranmission was not the equal of the Allison.  So I went into the deal with my eyes wide open.

As it turns out, the Ford averages 2-3 miles per gallon less than the Chevy in all types of driving.  On a trip that I make frequently, the Ford gets l6 mpg where the Chevy got l9. I am certain that a significant portion of the difference can be accounted for by its larger frontal area and higher coefficient of drag.  I don't know the exact numbers, but put them side by side and the difference is obvious. Another part of the difference is certainly that the Ford engine is less efficient than the Chevy.

The bottom line is that I am much happier with the Ford than the Chevy, and I think I can live with the mileage.  Also, Ford finally got it right with the longer rear leaf springs and coil front springs.  It actually rides better, in my opinion, that the Chevy. Also, since the truck is a 4 wheel drive, I am happier with the Ford's heavy duty front end system.

If fuel mileage is extremely important to you, the Ford is not the truck to have.  Keep in mind that any of the Diesels with automatic transmission can be made to get poor mileage with aggressive driving habits.

I have spoken with a few insiders about the prospect of improving the Ford mileage.  It's too early to tell, but the addition of the RIGHT cold air intake, particulate filter back exhaust system and tuner would probably add 2 mpg and improve driveability.  Installing a tuner, however, could definately cause you warranty problems.

As someone once said, "You pay your money and you take your chances."  

I drive 08 6.4L in Houston,Tx as a daily driver at 14MPG empty  

I HAVE A FORD  F250 YEAR 2000 IM LEAKING FUEL IN BETWEEN THE OIL PAN AND TRANSMISSION PLEASE HELP I NEED INFO YOU CAN  E-MAIL ME  MUDGRIP@YMAIL.COM