Real-world test: Difference in solo vs. towing fuel economy in pickup trucks

By Russ and Tiña De Maris

Everybody wants something for nothing – or so the saying goes. In the RV towing world, pulling a travel trailer without pumping tons of fuel has a big appeal. Truck makers have responded with differing thoughts, and one of them, Ram, brought a 3.0-liter diesel engine back to their Ram 1500 in the 2020 model year.

Called the EcoDiesel, the revamped return claimed a 260 horsepower, 480 foot-pounds of torque. As to fuel economy? The EPA’s projected economy is said to be as high as 29 miles per gallon on the freeway, with a low of 21 mpg in city, and 24 miles per gallon combined. All well and good – but what happens when you stick a little weight on the back side?

Matt Barnes, a writer with PickupTrucks.com, had the same question – and instead of just head scratching, put the question to a practical test. Barnes took the EcoDiesel-equipped Ram truck over a 107-mile test run, first solo, then with a “brand-unnamed” 5,000-pound travel trailer. He included freeway, city, and grade-pulling (up to 10%) in his route to check the difference in economy with some interesting results.

Unsurprisingly, solo driving did the best for him. While the truck’s fuel computer suggested the solo route he drove was a respectable 26.4 mpg, in reality by filling up and doing the math, the actual fuel economy worked out to 25.7 – about a 3 percent difference of opinion. No doubt enhancing the truck’s fuel-ability is a clever program that lowers the truck’s suspension to reduce air drag. The system automatically kicks in at 62 miles per hour. But what happens with a bit of dead weight?

While Barnes didn’t call-out the manufacturer of the test trailer, if the photo he included was indeed showing the test rig, we’ll spill the beans. A Springdale, with at least one slide-out, was the towing load for the test. The trailer is said to be 5,000 pounds, with a 600-pound tongue weight. Barnes points out that the trailer had “the worst aerodynamics of any trailer I’ve tested (for my day job, I am a product engineer for Progress Mfg. Inc., a manufacturer of hitches and trailer products). In other testing, this trailer caused other vehicles to return worse fuel economy than trailers weighing more than double its weight.”

Results? Over 100+ miles of “over hill, over dale” the actual fuel economy worked out to 12.1 mpg – far lower than the optimistic fuel computer in the Dodge, which claimed 13.2 mpg. In this case, the truck’s suspension was set to normal height, following Dodge’s recommendations for towing.

By our calculations, the difference in fuel economy between solo and towing was nearly 72 percent. In contrast, our ancient-but-reliable Ford 7.2-liter diesel averages solo about 15 mpg, and when we tack on 11,000 pounds of travel trailer, our average works out to about 10.5 mpg – a far more impressive loss of only 35 percent. To the Dodge’s credit, however, Matt Barnes noted that he did his best to keep his test combination at the speed limit, on at least one grade, it was a “pedal to the metal” affair. Since we’ve been accused of “driving like Grampa,” that could make for a bit of difference.

Barnes’ account is an interesting read, and you’ll find it here.

Story updated, 7/7/2020 to accurately reflect Ram trucks are no longer name-affiliated with Dodge. Hat-tip to Reader Greg.

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