Big Wheels are quietly getting more efficient

By Warren Brown

WASHINGTON — Fuel economy research lacks the news value of a politician allegedly cheating on his wife with prostitutes. It also pales in comparison with the latest media reports on the mental status of Britney Spears, or the endless contest for the Democratic presidential nomination.

When research on fuel economy leaves the arena of personal transportation, it enters the news equivalent of a black hole, compressed by the gravitas of everything else happening in the world and rendered practically meaningless.

But research on getting the most miles per gallon out of vehicles that carry the most people and the most stuff is critically important to the global economy and environment.

And while the rest of the world occupied itself with tales of hanky-panky in high places, movie star divorces and pregnancies, and more mundane matters such as continued death and mayhem in Iraq, there have been some interesting developments in big-wheels fuel economy, notably with the recent introductions of Volvo’s parallel diesel-electric hybrid, long-haul commercial trucks and the introduction of two-mode, gas-electric hybrid city buses and sport-utility vehicles.

We’ll start first with Volvo Trucks, which is not to be confused with the company that makes Volvo Cars, which is owned by Ford.

Diesel-electric engine

Volvo Trucks recently has been wowing transportation and energy officials in the United States and Europe with exhibitions of 18-wheelers powered by its new D7 diesel-electric engine with an integrated starter/alternator motor, the latter of which Volvo dubs I-SAM.

To be succinct, the D7-powered 18-wheeler delivers up to 35 percent better fuel economy over commercial trucks with traditional diesel engines. In a world where oil prices have topped $110 per barrel and where the rising price of oil pushes up the price of everything, that kind of improvement in fuel economy could bear good tidings for trucking companies and consumers alike.

The D7/I-SAM system uses a small diesel engine in tandem with an electronically controlled alternator motor that eliminates wasteful diesel idling at “stop” and that starts the engine at the touch of the accelerator. The electric part of the drive system can move the truck at low speeds. The upshot is a more fuel efficient 18-wheeler that also produces less particulate matter and other tailpipe pollutants and that has the added grace of running more quietly.

Volvo Trucks, which owns Mack Trucks in the United States and Canada and Renault Trucks in France, eventually will use the D7/I-SAM system throughout its commercial truck lines. Companies such as Coca-Cola already are lining up as customers. Who knows? Although we’re likely to be paying as much as $4 a gallon for regular gasoline in the summer of 2008, we might still be able to find a Coke at a bargain.

Another good tidbit is that Volvo’s D7/I-SAM system can be used in city buses and other mass transit services, thus saving fuel by moving more people with greater fuel efficiency.

Gas-electric hybrid

The same is true of two-mode, gas-electric hybrid system jointly developed by General Motors, BMW, and what was DaimlerChrysler before the breakup last year of Daimler and Chrysler.

The two-mode hybrid is engineered to produce the best fuel economy depending on vehicle speed and load. It can use either a fossil-fuel engine or alternatively fueled engine in tandem with computer-controlled electric system, employing a nickel metal-hydride battery and electric motors, to do its job. The upshot here is a 25 to 30 percent improvement in fuel economy in city buses, and up to a 50 percent improvement in city fuel economy in big sport-utility vehicles such as the Chevrolet Tahoe Hybrid and the GMC Yukon.

GM has been using similar two-mode systems in city buses since 2003. At latest count, an estimated 700 buses using the GM system are running in 60 cities in North America.