The 6.2 diesels do well enough for High mpg without modification (Get rid of EGR and use dual pipes helps for sure). I have a dual exhaust 6.2 with a 2.73 rear and a 700r4 overdrive transmission. I do not baby my truck for mpg's. I am just as likely to hit 85 mph as to stay at 65mph. So when I say I never get less than 22 mpg on the highway believe it! I know I could get 26+ if I tried but that would require concentration and ruin all the fun of saving 5 minutes. I also get 15-16 mpg in the city. And I mean Washington DC, stop and go traffic where the general speed limits on main thoroughfares is 25 mph! So my combined city/hwy is 18-20 mpg. While my low mileage Humvee engine was being installed I borrowed a 1995 Dodge Ram 3500 w/360 magnum v8 & dually tires. Averaged 8-10 MPG. If I stayed in town hauling a load or my foot got heavy it got down to 6 mpg!! I was sure glad to get my diesel back. And diesel costs are typically below premium, so I figure less than 10% added pump cost for 30-50% better mpg. The increased costs of oil/filter changes are offset by relative lack of tune-up issues and longer term reliability IMHO. Further, despite all the naysayers, I believe diesel will be the last internal combustion holdout. We can make real biofuel for diesel out of weeds. All we need is a solvent and vegetable oil. Try that in your gas engine. Finally, I have never owned a full sized Van or pickup that averaged over 15 mpg before and I have owned six and driven more than I can count. Working on this '86 Sierra is a breeze too. I will never own anything else as a daily work truck other than a 84-87 Chevy/GMC with a 6.2 diesel. I
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