First off I'm a part timer in the green industry. I currently have a Chevy 1500, and I drive about 25 miles each way to work. Then I mow through the week. How much of a differnce in gas mileage is their between a standard gas engine vs. the Chevy HD diesels. Repairs? I'm wanting to get a crew cab 4 x 4 and I really like the Chevy HD's.