What is the most cost-effective way to increase fuel mileage on a Dodge diesel?

Considering their size and power, Cummins-equipped Dodge trucks have always gotten pretty good fuel mileage. However, Chrysler had to make a number of market-driven compromises when it came to engineering, and many of those came at the expense of fuel mileage.

Freewheel Hubs

Oddly enough, one of the simplest ways to get a meaningful fuel economy increase has nothing to do with the engine itself. Dodge uses auto-locking hubs that allow the drivetrain to spin while four-wheel drive is not engaged, which sucks power and cuts down on fuel economy. Free-spinning hub conversion kits cost around $600, so they're not the cheapest route. But they are almost certain to gain you between two and four miles per gallon. Considering that many Cummins Dodges only get around 20 to 25 miles per gallon, that's a pretty respectable 10 to 20 percent increase in economy, so it won't take long to recoup the investment.

Intake and Exhaust

A freer-flowing intake and exhaust is guaranteed to free up some horsepower and fuel economy. While aftermarket systems are always available, you can expect to spend at least $600 for a bolt-on dual exhaust. Electric exhaust cutouts will accomplish the same task for less than a third the cost of a bolt-on kit. Skip the expensive aftermarket intakes, and get a universal rubber tube and inexpensive cone-style air filter. Between these two modes, you're looking at at least 20 more horsepower and at least 10 percent more fuel economy for less than $300 total.

Electric Fans

Electric fans are always worth the power and economy, especially when replacing the Cummins engine's massive windmill. If you want to do it "right," get an aftermarket electric fan kit for $400. If that's a little too spendy, consider using a junkyard electric fan setup from a 3.8L ford Taurus or V8 Lincoln MKVIII. These fans are popular upgrades on the hot-rod market, and flow a lot more air than either Ford really needed. If you go the junkyard route, expect to spend about $30 to $40 for at least 15 more horsepower and get about 8 to 10 percent better fuel economy.

Power Programmer

From $400 to $700, power tuners (computer re-programmers) aren't the cheapest thing on the market, but they will turn your truck into a fuel miser when you need it to be and a powerhouse monster when you want it to be. A power tuner is the easiest possible upgrade; just plug it in, punch some buttons and drive off. Several companies (including Banks and Bully Dog) offer tuners with fuel-sipping programs that will net you an easy 15 to 20 percent gain in fuel economy. If you don't want to spend the money on a retail unit, check out eBay or other online retailers; used tuners often run less than half the retail cost and do the exact same thing.

Source:

Four Wheeler: 19 Ways to Increase Fuel Economy

Diesel Power: First-Gen Cummins buildup

Diesel Power: Cummins economy upgrades

More Information:

YouTube: Diesel for Massive Power and Economy