Most business decisions are based on ratios, thresholds or tipping points. Let’s go ahead with the expansion project if we can raise this amount of capital; let’s give a bonus to the sales guy if he reaches the 10% growth target; let’s buy roof fairings for our trucks if they give us 3% better fuel economy, etc.

There’s also a threshold to take into account – along with the type of application – when considering the purchase of a gasoline engine truck instead of a diesel. That tipping point usually is mileage of around 40,000 kilometers and less per year. It’s no golden rule, but that’s roughly when the lower purchase price, maintenance and training costs associated with a gasoline engine can compensate for its generally higher fuel prices and lower residual value.

And looking at the gasoline engine’s popularity in the medium-duty segment over the last couple of years, obviously many fleets and owner-operators whose core business isn’t longhaul trucking already resolved the 40K question.

Wide gasoline offerings
Brian Tabel is executive director of marketing at Isuzu Commercial Truck of America (ICTA), an OEM that has offered a gasoline option – the GM 6-liter Vortec V8 – in addition to diesel engines in its cabover Class 4 trucks since 1994.

“Our old adage was if a customer drove 25,000 miles (40,000 kms) a year and less, cost-wise, probably a gasoline engine was the way to go,” he says.

“As additional requirements on diesel have affected the whole industry from diesel particulate filters (DPFs) and selective catalytic reduction (SCR), some of those customers that drive 30,000, maybe even 35,000 miles a year, (50,000-55,000 kms) have stretched into the gasoline engine just so they don’t have the DPF requirements or SCR involvement in their vehicles,” Tabel adds.

Mitsubishi Fuso also picked GM’s Vortec for its recent announcement that it would also offer a V8 gasoline option on its Classes 4 and 5 trucks, Fuso now being the only OEM to offer a gasoline engine in a Class 5 cabover truck. Compared to the regular 3-liter Fuso diesel engine, GM’s gas V8 has twice the displacement.

This extra three liters allows quite interesting performances: 297 hp compared to 161 for the diesel (84% more) and 22% more torque: 361 lb.-ft. with gasoline instead of 295 with the Fuso diesel.

“We believe we’ll be matching what the current market is showing, which is basically 60% diesel, 40% gas,” says Bill Lyons, vice-president of sales operations at Mitsubishi Fuso Truck of America (MFTA), when asked about the expected breakdown of sales per engine type.

Even though it shares the same GM engine base that the competing Isuzu has been offering for years, Fuso insists that the V8 has been fine-tuned for its own users.

“This engine is a result of our collaboration with Freightliner Custom Chassis (FCCC) and we jointly decided to source this engine from PSI (an engine integrator headquartered in Wood Dale, Ill.) and GM and that engine has been redesigned, especially in terms of software, for the Daimler needs, for Fuso and Freightliner,” says Otto Schmid, MFTA’s director of product management.

As Schmid mentions, FCCC also uses the GM 6-liter V8 gasoline engine for vehicles based on its MT-45 and MT-55 chassis, including walk-in vans. According to FCCC, different versions of the MT chassis available with the gasoline V8 have Gross Vehicle Weight Ratings (GVWR) going up to 23,000 lbs, which is in the middle of the Class 6 range.

Those GVWR figures tend to confirm that the 6-liter Vortec can, indeed, power Daimler commercial vehicles beyond Class 5, as states Fuso’s Schmid: “This engine is a so-called ‘heavy-duty OBD certified engine.’ This means we can offer this engine in Class 4 and 5 and above.”

There seems to be a market for gasoline trucks of that size. For instance, RAM offers a gasoline (6.4-liter Hemi V8) version of its 5500 chassis cab model that boasts a 19,500-lb GVWR, which is at the border of Classes 5/6.

Right now, Freightliner doesn’t offer a gasoline option in its regular M2 medium-duty Classes 6/7 trucks, says Kelly Gedert, director of product marketing,

Freightliner Trucks and Detroit Components. But gasoline truck power is already available in the Daimler family in case Freightliner changes its plans for the M2.

At Navistar, Steve Gilligan, vice-president, product marketing, thinks that gasoline could even be helpful in heavier segments, as high as Class 7: “Gasoline is obviously a viable alternative in Classes 4 and 5 due to less demanding applications and shorter vehicle life cycles. An ongoing percentage of the market in Classes 6 and 7 will likely consider gasoline, as will any applications that are dependent on conversion to spark-ignited propane and/ or natural gas. Gasoline will have an ongoing number of adopters in Classes 6-7, but we don’t expect that this population will significantly exceed 10%, unless some improvements are made in the areas of gasoline fuel economy or durability.”

According to Gilligan, Navistar is giving the gasoline option serious thoughts. “We are researching gasoline possibilities,” he says.

Even though many OEMs are opting for the Vortec, supply capacity shouldn’t be an issue at GM, assures Tom Read, with GM Global Propulsion Systems communications. “Our manufacturing plants are agile and can adapt swiftly to changes in the market,” Read says.

Pros and cons
Because they are so robust and durable, diesel engines still have bright days ahead of them, especially in longhaul and harsh vocational applications. Yet, what makes the gasoline alternative appealing to many is the absence of all the hardware that was gradually grafted to diesel workhorses to comply with evermore stringent emissions regulations, ie. complicated aftertreatment systems involving diesel exhaust fluid (DEF) injection with a separate tank, passive/active regeneration, particulate filters and the like, which sometimes make maintenance managers go berserk.

“A portion of the market experienced a variety of product quality issues with diesel engines provided by a variety of OEMs. As a result, some of these customers have considered moving to gasoline engines,” notes Gilligan.

Sad but true, the more an engine design is complicated, the more likely it is to fail. “Every emissions level increases the complexity of a diesel engine, much more than a gasoline engine,” Schmid says.

His Fuso colleague Lyons, concurs: “A big portion of our customer base are small business owners and they’re experiencing what we termed as ‘diesel fatigue’,” he says, referring to above-mentioned modern diesel complexity.

Isuzu’s Tabel also thinks diesel aftertreatment systems have incited some customers to walk away from them.

Schmid at Fuso agrees on that point. “From a driver’s perspective, the daily maintenance and the checkpoints are much simpler (with gas). The only thing you have to look at basically is the fuel and the oil in the engine.”

Capital investment can also be an incentive for potential customers to explore the gasoline avenue, as diesel trucks usually cost several thousand dollars more than a gasoline equivalent. Granted, the lower price of diesel fuel can offset that price difference over time, but a carrier needs to accumulate high mileage to get an interesting ROI, thus the 40,000-km per year mark that’s considered to be a threshold from which diesel makes more business sense than gasoline.

“Switching to gasoline requires a willingness to compromise on other areas, primarily durability, fuel economy, and residual value. While the differences are not as pronounced as they were in the past, the diesel engines still offer measurable advantages in these areas. The current generation of diesel engines have demonstrated improvements in reliability versus the first-generation SCR and EGR engines,” notes Navistar’s Gilligan.

High pressure injection in diesel engines is another important factor, reminds Fuso’s Schmid. “The engine we are using in the gas truck is relatively lightweight. A diesel engine always needs more material because of the significantly higher pressures in the combustion chamber. So, a diesel engine with the same displacement is always significantly heavier than a gas engine.” That means a payload advantage for the latter.

Yet, it doesn’t have to be black and white, as the two types of engines can co-exist within the same fleet depending on different routes’ requirements, which is not unusual according to Tabel.

“One thing that we have seen over the last three to four years is customers that are right-sizing their fleet,” he says, adding, “before the Lehman shock recession, a customer would buy one truck, one GVW and that’s what he ran for his whole fleet.”

That was before truck purchasers really asked themselves the 40K question.