If you see Steve Kron’s 2001 International IHC 9400, you’ll likely do a double-take. Kron has heavily modified the truck over the years, including non-OEM aerodynamic headlights, and a bumper and fenders he pulled off a 2011 Mack Vision. And that’s just the exterior.

Look under the sheet metal and you’ll find a 6x2 drive axle with a 2:50 ratio from of a 2007 International ProStar. Pull the hood open and you’ll see a variable geometry turbocharger from a recent DD15 diesel engine fitted to his 2001 Detroit Diesel. And those are just a few of the most high-profile modifications. The truck is fitted with dozens of others, both major and minor, including several homemade, one-off aerodynamic components. 

“People either love it or they hate it,” Kron says with a chuckle. But don’t be too quick to laugh. Kron routinely logs over 10 mpg and claims a lifetime average of 9.21 mpg over more than 1 million miles. And he’s racking up those numbers with an Eaton 10-speed manual transmission and almost none of the high-tech aids many drivers take for granted.

So what’s his secret? Kron says it’s simply driving as slowly as time, productivity and conditions allow. “I try to run between 57 and 59 mph as much as possible,” he says. “I might get up to 62 mph. But if you start getting above that, you need really good aerodynamics to get good fuel economy.”

Kron says the advent of mandatory electronic logging devices to track driver hours has forced him to drive faster than he’d like to at times. 

“You don’t always have the luxury of focusing on fuel economy,” he says. “Because you’ve got to make money. And sometimes, there’s no choice but to make up time. You might only need another half an hour to get your work done. But now, there’s no way to make that time up,” without the ability to “fudge” his end time, as he would have using paper logs.

Even at his slower pace, Kron says he still is easy on the pedal at all times – particularly at slow speeds, when even slight throttle inputs can exponentially increase the rate of fuel flowing through the engine. 

“You can have the most fuel-efficient truck in the world, but if you’re jackrabbit-starting all the time and speeding, you’re not going to get good fuel economy,” he says. “I also work the hills. I don’t go too fast down them and let gravity do most of the work getting me back to 55 mph.”

Another big no-no in Kron’s book is braking, which he only does when safety or circumstances require it. 

“Almost every time you step on the brakes, you’re going to have burn fuel to regain whatever momentum you lost. So you need to minimize that disadvantage as much as possible by looking ahead and planning accordingly. The trick is to maintain as much forward momentum as possible while being as safe as possible.”