Actually, the gas mileage is better on the 3.0 than the 4.4/4.8. (I owned a 2006 3.0 which I traded in for a 2005 4.4). On average, the 3.0 wil get about 1.5 mpg better than the 4.4. While in-town driving results in less of a mpg difference, the 3.0 is much more fuel effiecient than the 4.4 with highway driving.

Based on my experience with both the 3.0 and 4.4, I would recommend the 4.4. It has a substantially better accelleration, which is good for when you have to pass someone on a 2-lane highway, and also makes it more fun to drive.