It’s a tantalizing prospect to say the least: spec’ing an engine with near-diesel horsepower and torque without a hefty premium or space-usurping emissions control system. All while using a cheaper yet widely available fuel to boot. That is the enticing proposition offered by gasoline engines in the medium-duty fleet space.

Like so many of the decisions in the medium-duty truck world, the choice of gas vs. diesel isn’t so cut and dried, especially when it comes to the all-too-crucial total cost of operation (TCO) and lifecycle cost calculations. The sheer longevity of diesels, or B50 life, is one factor working against their gasoline counterparts in the TCO equation. Another is residual value, with diesel-powered used trucks commanding a far higher premium than similar gasoline-equipped chassis.

Still, the vastly cheaper price tag for a gasoline-powered, medium-duty truck remains a significant head-turning quotient in the fleet world these days.

“Not so long ago, the gas vs. diesel equation handily favored diesel: Diesels offered more power and you received a significant payback because of the low cost of diesel fuel relative to gasoline and diesel’s better fuel economy,” explains Ken Gillies, manager of truck ordering & engineering at GE Capital Fleet Services.

“Now that equation has been flipped on its head,” he says. “Diesel fuel is more expensive than gasoline, and the fuel economy gap isn’t as wide anymore. Also, the addition of emissions control technology to diesel engines added significantly to the initial purchase price of diesel-powered trucks.”

That role reversal of the engine cost footprint convinced Ford Motor to offer its 2012 model F-650 Super Duty with a redesigned 6.8L three-valve V10 Triton gasoline engine that cranks out 362 hp. and 457 lbs.-ft. of torque. Coupled with a Ford 6R410 6-speed automatic transmission featuring double overdrive gears, that engine now offers near-diesel fuel economy and performance in many medium-duty applications, notes Todd Kaufman, Ford’s F-Series chassis cab marketing manager.

“Now we have a far more capable engine that costs thousands less than a similarly equipped diesel-powered truck,” he explains. “For vehicles such as single-axle municipal dump trucks or highway snow plow operations—typically low-mileage trucks—you’ve got an opportunity to significantly lower acquisition and operating costs across the board.”

INITIAL PRICE CUT

Kaufman says the average savings for a gasoline- powered F-650 compared to a diesel model is $8,300 per truck. This is largely because the expensive emissions control system, which includes a diesel particulate filter (DPF), selective catalytic reduction (SCR) package, and diesel exhaust fluid (DEF) tank, isn’t required on trucks spec’d with gasoline engines.

“There’s other ongoing operational and maintenance savings to that as well, as you don’t need to worry about DPF regeneration, SCR system upkeep, and DEF consumption,” he points out.

“So now the question really hinges on what type of vocation/work the truck is expected to perform, and do you really need the low-end torque that is the hallmark of the diesel,” adds GE Capital’s Gillies. “With customers, we talk about engine loads and what they really need in terms of power at the end of the day.”

One of many spec’ing issues for gasoline engines, though, is that you are far more limited in what models are available for particular trucks, says Gillies. “You’ve got the V10 Triton from Ford with some gasoline options for Isuzu’s NPR model and other cabovers, so the footprint for gasoline engines is somewhat limited in the medium-duty space,” he explains. “Also, you can look at using a smaller diesel engine as well, not only to reduce initial cost but to improve fuel economy.”

Then there’s engine longevity. The B10 and B50 life of a typical diesel engine still far exceeds that of a comparable gasoline engine.

“We remain hesitant to say choose gasoline over diesel. We’re hesitant to enter that discussion many times because of the work our customers’ trucks perform and the driver acceptance of a gasoline engine in many vocational applications,” Gillies explains.

Scott Perry, vice president-supply management for Ryder System, understands that hesitation very well. “There is some movement to a gasoline platform in medium- duty but only in low-mileage applications,” he says. “We typically look at the engine from a lifecycle perspective.

A diesel engine is typically more robust and has a long lifecycle as well as a lower operating cost. True, the DPF and SCR systems make it more expensive. But from a maintenance standpoint, the DPF only needs cleaning rarely, usually in the truck’s second life with the second owner.”

Again, stresses Perry, the big driver in Ryder’s medium- duty calculations is lifecycle cost. “You have to take and factor that over a longer life expectancy compared to a gasoline model,” he points out. “Sure, gasoline has a lower upfront investment compared to the premium for diesel. Even though diesels have emissions control systems, they still are not as complex as gasoline models. Gasoline engines are still not excluded from carbon emissions regulations.”

RESIDUAL EFFECTS

Future fuel economy standards in the gasoline engine space will probably lead to the addition of engine components and emissions control technology that will no doubt bump up the cost of gasoline engines and the truck chassis they are fitted into, Perry suggests.

“Finally, there is TCO and how residual value fits into TCO,” he emphasizes. “Residual value is very important. If you consume 99% of a gasoline truck’s asset life in the first ownership, you’ll have little residual value left. It’s all about the economic life of the asset, and that’s a function of a bigger price point than just acquisition and operational cost.”

On the near-term horizon, however, Perry believes there may be a window of time when the gasoline product is very viable in terms of cost savings.

That’s what makes Ford’s Kaufman so confident. “Budget cuts and financial restrictions are daily realities for city and town governments, so finding ways to save money is imperative,” he explains. “For municipalities and others seeking a cheaper alternative to replenish an aging medium-duty truck fleet, it’s the gasoline engine, a variant that costs thousands of dollars less than diesel-powered trucks of its size.”

Yet Brent Gruber, director of commercial vehicle practice at research firm J.D. Power and Associates, points out that you shouldn’t examine the costs and savings of gasoline and diesel engines without looking at the medium-duty truck as a whole.

“You can’t look at diesel or gasoline engines in the medium-duty space as stand-alone products,” he stresses. “You really need to focus on the medium-duty truck as a whole and how those two different engines factor into the entire truck picture.”

In his opinion, Gruber says a fleet looking at gasoline in the medium-duty space is trying to minimize cost as much as possible, both in terms of sticker price and fuel expense. “The cost of new diesel-powered trucks has increased very rapidly, so if fleets can find a lower-cost solution, they will switch to it,” he notes.

There are trade-offs along this line of thinking, Gruber warns, especially as diesels offer better low-end torque.

“But in many cases, fleets are deliberately trying to make do with less—to rightsize their trucks where possible in order to reduce cost,” he continues. “If you can lower your cost by switching to a gasoline engine and still get most of what you need done, you’ll do it. TCO is important, but the poor economy plus the rising cost of the diesel powertrain and diesel fuel means that many fleets may switch to gasoline if they can do it.”

History, however, indicates that higher costs, especially where diesel fuel is concerned, may not necessarily provide enough benefit to convince fleets to embrace gasoline, says Jonathan Starks, director of transportation analysis for FTR Associates.

“Back in 2007 and 2008 [when diesel prices neared $5/gal. in the U.S.], we thought we’d see a big shift to gasoline in the medium-duty space due to the initial cost savings,” he says. “While there has been some shift, it has not been dramatic over the last five years.” Starks does believe that more shifting to gasoline could occur over the next five years as the impact of the 2010 emissions changes continue to be felt among diesel- powered medium-duty fleets.

COMFORT CHOICE Still, he says fleets need to see a lot of analysis in terms of whether diesel or gasoline makes the most fiscal sense over the lifecycle of the vehicle.

“They need to look at the cost and if the truck will do what they need it to do with a gasoline engine. If they are comfortable with the results, they will make the switch,” Starks notes. “The other part of this, though, is that medium-duty fleets know how to operate diesels and work on them, not so much on gasoline truck engines. A bigger player might have both diesel and gasoline in its fleet, but that’s usually rare.”

Eric Starks, president of FTR Associates, offers another reason the transition from diesel to gasoline remains slow: There’s just not a lot of demand for gasoline trucks on the used market. “Residual value and the overall life expectancy of the equipment are the two main issues when it comes to spec’ing gasoline over diesel,” he says.

Ultimately, GE Capital’s Gillies believes it all comes down to balancing cost with performance.

“It’s simply about what is the best set of truck specifications for the job it’s expected to perform,” he says. “That’s why it’s important to note that because of all the changes that have occurred in trucking over the last decade, and to diesel engines in particular, customers are now far more open to discussing changing their operations. They are a lot more willing to go back to square one and take a fresh look at their fleet. They are much more open in their thinking.”

And that openness may be all it takes to give the gasoline engine a fighting chance to make fresh headway in the medium-duty market.