Through the years, we've discussed fuel economy many times here at The Diesel Page. Common strategies for maximizing MPG include driving slower, reducing weight, reducing drag, and optimizing both vehicle and engine tune. To one degree or another, all of these areas have an effect on fuel efficiency. We'll include all of the common strategies for increasing fuel economy in our new MPG Project, as well every other component and even including vehicle choice that combine to produce the highest possible fuel economy for a GM V-8 diesel powered vehicle.

Increasing fuel economy has always involved compromise... Driving slower than you're used to, towing a smaller trailer, and hauling lighter loads are all a part of this compromise. Compromise may also play a part in vehicle choice. The fuel crunch we all dealt with post Katrina has rearranged priorities for lots of folks. Some have even had to choose between driving their vehicle or not. One important element behind launching this MPG Project is to be able to drive as much as (or more than) you did pre-Katrina, while spending less at the pump.

Compromise is key to developing a vehicle for maximum fuel economy. However, compromise shouldn't cut so deep as to force a major life-style change.

Whether you need a fuel efficient vehicle for a mobile service business, or are interested in hauling bed toys, like motorcycles and watercraft, as well as towing a reasonably sized travel-trailer, "Sport Utility" shouldn't go the way of $2 diesel fuel.

Ron Pierce's 21' Airstream

What we need is a vehicle that maintains the usefulness and most capabilities of a 1/2-ton full-size pickup, yet delivers at least 30 miles per gallon while driving solo at Interstate speeds. We also want a vehicle that is both great looking and fun to drive.

Engine and drivetrain modifications discussed in this series will apply directly to all 6.2/6.5-powered pickup trucks and Suburbans, but we'll be taking this MPG quest to the next level. To achieve our goal of 30-mpg, we need to choose a pickup truck that weighs less than a typical 1/2-ton pickup and offers a lower coefficient of drag. So, just what sort of GM pickup are we talking about?

The 1968-72 EL Camino are among my favorite classic-muscle vehicles produced by GM. Currently undervalued in the C/M segment, the El Camino offers a whole lot of "sport" as well as "utility". Weighing in at 3200-3800 lbs (~1000 lbs lighter than a 1/2 ton 2WD GM pickup) and offering a lot less drag, the El Camino should satisfy our needs for a fuel economy platform.

The 1972 EL Camino photos shown here are courtesy of the Camino Mania web site, and though the color will be different, represent what our 6.5L diesel powered El Camino will look like. That's right, a 6.5L diesel!

But not just any 6.5. This engine will be optimized for fuel efficiency. All aspects of the cylinder heads, pistons, valves and valve train, and fuel injection system will be chosen from a broad selection of optional components that when combined will deliver stellar fuel economy.

In addition, the remaining components of the drivetrain will be chosen primarily for fuel economy. For transmissions, we'll likely be using an optimized TH700R4 overdrive auto, and differential gearing will be chosen that produces 1800-rpm at 65-mph. We'll go into the drivetrain design and cover all of the engine modifications in a later MPG update.

The surge in fuel costs we saw in 2005 was eerily reminiscent of the late 70's and early 80's when the cost of fuel doubled and domestic auto makers saw their market share plummet. First appearing in the 1982 model year, the 6.2L diesel was designed as an alternative to the 305 V-8 gasoline engines of the same period, having nearly the same power but delivering more than twice the fuel economy. Dejavu... With fuel costs soaring above $3 a gallon in 2005 - some 23 years later, a renewed interest in fuel economy has put the 6.2/6.5 back into the spotlight.

This introduction is the first of many articles and technical discussions that'll appear right here in The Diesel Page in the coming months as the 6.5L Diesel El Camino fuel economy project comes together.     TDP