For Landon Sproull, chief engineer at Peterbilt Motors Co., it's no accident that the OEM's new Class 8 diesel-electric hybrid tractor is painted green, for the color green represents several key goals this prototype must achieve: reduce pollution, reduce fuel consumption and, most importantly, reduce fleet costs. If hybrid technology can't save enough greenbacks to pay for itself, and then some, it will eventually die on the vine.

“It's part of looking at a hybrid truck as a complete package offering fuel savings, power assistance and a no-idle system all in one,” says Sproull. “But all of that has got to add up to savings over the ownership cycle of the vehicle. That's the acid test.”

A joint venture formed by Peterbilt's parent company, Paccar, and Eaton Corp. plans to develop a Class 8 hybrid truck by 2009. Eaton is providing the guts of the hybrid system — a traction motor married to a Fuller UltraShift 10-speed automated transmission and four lithium ion batteries — while Paccar subsidiaries Kenworth and Peterbilt are responsible for the chassis and diesel engine, as well as the engineering needed to bring everything together.

“There will of course be an up-charge for buying a hybrid tractor, although we don't know how much at this point because we are using such a low volume of components to build it,” says Bill Jackson, Peterbilt's general manager. “But we see many opportunities: fuel savings, power assistance on hills, plus a way to operate the truck's heating and air-conditioning system without running the engine, [which is] a big issue as anti-idle regulations increase.”

Gary Moore, Kenworth's assistant general manager, adds that although the fuel economy savings in a heavy-duty hybrid wouldn't be as great as those being experienced in hybrid medium-duty vehicles, the payback is still there.

“Even a 1/10th improvement in fuel economy would be a huge savings to OTR fleets,” he says. “And there are other benefits, such as power assist on hills, that can outweigh the additional weight a hybrid system would add to the vehicle. There's going to be a payback, but we are just now getting into this, so we need to see where the benefits develop.”


For Wal-Mart Transportation, which is taking delivery of Peterbilt's hybrid Class 8 truck for testing, fleet efficiency is the number-one reason it's so interested in hybrid technology, because greater efficiency means a better bottom line.

“We've set a goal to double the efficiency of its fleet (using 2005 standards) by 2015,” explains Tim Yatsko, senior vp-transportation at Wal-Mart. “We're looking at a number of innovative technologies, including auxiliary power units (APUs), fuel-efficient tires, aerodynamic parts and diesel-hybrid trucks. Currently, we have entered into working partnerships with ArvinMeritor, International Truck & Engine Corp., Peterbilt and Eaton to develop heavy-duty, diesel-hybrid trucks, and we hope to see pilot versions by the end of 2008.”

Yatsko says hybrids should help Wal-Mart increase its fleet efficiency in metro areas where the vehicles travel at slower speeds.

“We are working to reduce the amount of time our trucks run their engines,” he says. “We've outfitted all of our overnight trucks with APUs and continue to explore other options to power the truck and its communication and auxiliary systems. At this time, however, our efforts for the hybrid trucks are focused on increasing the efficiency of the major components through the use of hybrid technology.”

To be sustainable, however, hybrids must deliver an adequate return on investment (ROI) to Wal-Mart, Yatsko points put. “That is the only way we continue to deliver cost savings to our customers so they can live better,” he says. “While we are not ready to share specific numbers, be assured that adequate ROI is built into our strategy and the project plans of the manufacturers.”

The same ROI exists for medium-duty hybrids, says George Survant, director of fleet services for Florida Power & Light (FPL). Survant's operation already uses three medium-duty hybrid bucket trucks built by International Truck & Engine Corp., and expects to deploy five more this fall.

“From a commercial perspective, the price needs to drop another 40% to really make it more compelling for fleets,” he explains. “The 27,000-lb. GVW diesel-only trucks we use typically cost $110,000 delivered. We think a hybrid version of the same truck at $135,000 delivered would create very compelling commercial potential.”


FPL's field-testing to date finds the hybrid trucks deliver at a bare minimum 30% better fuel economy than its diesel-only trucks. And if diesel prices stay where they are now — or go even higher — a fleet could pay off its initial hybrid investment in three years. Since many medium-duty fleets keep their trucks for up to 10 years, that leaves a lot of savings to fall right to the bottom line.

And that doesn't even count ancillary benefits, which could significantly boost those cost savings, stresses Survant. “At the job site, we can get two hours worth of use out of the [hybrid's] batteries before the engine needs to turn on for five minutes to recharge them,” he explains. “That means instead of running the [diesel] engine for six hours to power the aerial bucket in the course of a day, we run it only 15 to 30 minutes. That puts far less wear and tear on the diesel engine, which saves on maintenance.”

“That engine-off capability significantly boosts the fuel economy profile of a medium-duty work truck like this, potentially into the 40% to 60% range,” adds Jim Williams, director of new product sales for International. That could translate into a savings of $4,500 to $5,000 annually per vehicle if diesel fuel stays near $3/gal., he points out.

“Another key piece to our hybrid is that it's a parallel system [built by Eaton]. If for any reason the hybrid system goes off-line, the diesel engine can still power the vehicle,” Williams explains. “The truck doesn't go down…and that takes some of the fear out of the equation of new technology.”

Survant also notes that as part of FPL's effort to sell the hybrid concept to its work crews, the company kept the same size diesel engine, even though the hybrid's motor cranks out 57 horsepower. As crews become more comfortable with hybrid trucks, smaller displacement diesels can be used, improving the vehicle's fuel economy footprint even further.

John Walsh, spokesman for Mack Trucks, says other operations benefits can help improve the cost savings profile of hybrids. “For example, the electric motor serves both as brakes and generators during speed reduction, supplying electrical current to the battery,” he explains.

“The electric motor helps slow the vehicle, which extends brake life, and reduced brake wear is an important cost issue for many fleets in stop-and-go applications, such as refuse. And hybrids have significantly lower sound levels during start and acceleration when the electric motor and diesel engine are working together.”

Walsh says Mack's hybrid market focus is centered on low cabover and conventional truck chassis designed for both refuse and heavy urban distribution, as hybrid technology is well suited to create costs savings for fleets operating in those kinds of stop-and-go applications. “Fuel economy gains of up to 50% are achievable in applications such as refuse automatic side loaders running 1,000-plus cycles per day,” he notes.


Perhaps the biggest challenge confronting hybrid commercialization is time. So far, International is the only OEM ready to begin building hybrids on the production line, starting the first quarter of 2008, with other OEMs still field-testing prototypes. A lack of direct incentives also hurts hybrid development, leaving fleets to scramble for a mixture of federal and state grants to help mitigate steep price premiums.

“We believe our hybrid technology will be commercially viable. However, it will take several years to establish a robust hybrid market for heavy vehicles and eventually invest in large-scale production,” says Mack's Walsh.

“[Though] we believe that the savings for fuel and maintenance will be enough for a payback in a couple of years, depending on relative cost for conventional vehicles … incentives would help speed up the establishment of a robust market for hybrids that provides environmental advantages,” Walsh continues. “This would be similar to the incentives that have successfully established a market for cars with less environmental impact.”


The physical impact of hybrid technology on a commercial vehicle is being minimized as well, notes Todd Graham, account manager for Eaton's hybrid product. He explains that hybrid technology only adds about 300 pounds of weight to a Class 8 tractor. This is primarily due to the traction motor and power electric carrier (PEC), which holds four lithium ion batteries. Those batteries not only provide hybrid power, but replace the batteries that normally provide starting power. Eaton is shooting for a five-year life cycle for those lithium ion batteries.

Eaton's heavy-duty hybrid electric power system will be built using an automated manual transmission with a parallel-type “direct” hybrid system, incorporating an electric motor/generator located between the output of an automated clutch and the input to the transmission.

One added benefit will be its ability to recover energy normally lost during braking and store it in the batteries. When electric torque is blended with engine torque, this stored energy is used to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed, or operate with electric power only, says Graham.

Getting payback, of course, is the tricky part, he admits. “A hybrid's ROI is great in the medium-duty segment because owners keep their trucks 10 years on average,” Graham said. “In heavy-duty, however, many have a three-year trade cycle, so it's harder to accumulate the savings in that shorter time frame.”

Another key to a Class 8 hybrid is that it can minimize idle time without the need to install an APU, adds Peterbilt's Sproull. To handle normal tractor “hotel loads,” such as heat, air conditioning and nominal electric power for a television and other appliances, the hybrid's batteries would need recharging about every hour. Yet the main diesel engine would only need to operate for five minutes to fully recharge the system, he says, which is well within the idling limits mandated by many local and state ordinances.

“There is a groundswell of customer interest from an economic and environmental standpoint,” notes Bob Christensen, Kenworth's general manager. “We expect that interest to multiply as federal and state agencies become more aggressive in protecting the environment and reducing dependence on foreign oil. For these reasons, alternative fuels and hybrid technology are here to stay. That's why we are committed to designing and building fuel-efficient trucks that help reduce emissions and decrease customer operating costs.”


When Dunn Lumber Co. decided to buy Kenworth's first T300 medium-duty hybrid, the Seattle-based fleet wanted to make sure the truck met some key parameters: save money, perform well and show an environmental benefit.

“Our CEO felt environmental stewardship played an important role in acquiring this truck,” explains Mark Geyer, Dunn's fleet manager. “Seattle is a very environmentally-focused city. But we we're also going to face a $20,000 premium for this hybrid truck, so it has to perform.

Kenworth's T300 Class 7 hybrid, which can carry a payload of up to 16,000 lb., features a PACCAR PX-6 240-hp. engine, integral transmission-mounted motor/generator, frame-mounted 340-volt battery, and dedicated power management system.

From a performance standpoint, the truck provided more than enough power and payload to handle the job. And when the fuel economy improvement kicked in, the vehicle became even more attractive.

“It's still very early, but fuel economy is up an estimated 35% in the first few weeks of operation compared to one of our similarly spec'd Kenworth T300s,” says Geyer. “The truck is also extremely quiet, which is a big plus. More importantly, it achieved the balance we needed between being green and saving money through better fuel economy.”