To paraphrase the opening credits of "The Six Million Dollar Man," diesel engine manufacturers have plans for the engine system in fire apparatus: "We can rebuild it. We have the technology. We can make it better than it was before. Better. Stronger. Cleaner."

Sure, it's a pop culture reference, but it's apt. Emergency vehicles and the engines that drive them are shifting ever faster from the simple mechanical to, well, the bionic. Industry insiders say they're developing technologies to provide smaller engines that combine higher horsepower and torque ratings with better fuel efficiency and lower emissions - a combination that's usually diametrically opposed.

The trend of high-tech apparatus has been around for more than a decade. Aside from every company's push to improve its products, what's the impetus for the flurry of research and development on cleaner diesel engines? Three little letters: epa.

The agency's air-quality regulations are keeping intense pressure on the diesel engine industry. Last October, the epa and the Department of Justice announced a record $1 billion settlement with seven diesel engine manufacturers to resolve charges that the companies violated the Clean Air Act. The settlement covered Caterpillar, Cummins Engine, Detroit Diesel, Mack Truck, Navistar, Renault and Volvo. Most of the money will be used to further reduce emissions by building cleaner engines and retrofitting some existing ones.

EPA emission standards Most people in the industry are taking the ever-stricter epa regulations in stride. "We have a strong relationship with the epa," says Bob Carso, communications manager for Navistar's engine division. Navistar is well ahead of the emission-control curve, he says, citing its demonstrations of smokeless diesel technology in 1989 and 2004 emission limitation capability more than two years ago.

"epa emission standards first applied to diesel engines in the '70s," says Ron Berry, senior sales manager of Detroit Diesel's fire and emergency services group. "A lot of people said meeting those standards was impossible. Anytime you're tasked with something that exceeds the product you have today, it's a challenge. But we're taking the technologies that are available now and applying technologies that we're developing to keep the diesel engine viable in this market for the indefinite future."

David O'Brien, a marketing representative for Cummins, says the company spent a "very large chunk of money" to redesign its diesel engines. "While the new epa guidelines are stringent, our product enhancements were designed to meet or exceed them," he says. "For the future, we are looking for ways to reduce emissions while improving fuel economy."

Weight watchers, horse traders Some technicians who maintain fire apparatus seem generally pleased with the trends they see. "Engines are getting smaller, which helps reduce weight of vehicles," says Al Kloha, president of Circle K Service in Midland, Mich., and a board member of the National Association of Emergency Vehicle Technicians. In addition to increasing fuel efficiency through lighter-weight vehicles, O'Brien says, the smaller engine size offers easier access for apparatus technicians.

So is the fire service embracing the new lighter-weight engines? "In the fire service, we have not seen any significant movement toward the use of lighter-weight diesel engines unless there's an overriding problem with weight, such as local bridge restrictions," Berry says. "There are key issues with durability and reliability when it comes to using these lighter-weight engines.

"[Detroit Diesel's] Series 60 is designed to be a million-mile engine before major overhaul. Many of the new engines coming onto the market do not have that durability. It's important given some of the severe duty cycles a fire truck has to go through. It's sitting there at a fire scene pumping for a number of hours under heavy load." Durability should be a key consideration because the typical life cycle for a fire truck is 10 to 15 years, he says.

"We believe a modern, lighter engine like our C-12 can guarantee durability," says Jim Jeffries, Caterpillar senior account manager, "plus the smaller engine size lets you fit more firefighters in the front of the cab."

Berry says the over-the-road truck industry's move toward higher-horsepower engines is one reason they're being offered to the fire service more frequently. "With everybody increasing the horsepower of the engine platforms, it means there is a new breed of higher-horsepower diesel engines emerging," he says. "Do they have the long-term life of the past heavy-duty engines? Maybe not. But will they meet the needs of the fire service? That remains to be seen."

The trucking industry finds that higher-horsepower trucks tend to have higher resale value, an important consideration because they typically turn over their fleets every two or three years. That trend helps the fire service when they buy similar high-horsepower engines - it's easier to get parts and service because there are so many of the engines out there.

Purity control With this focus on horsepower, one may wonder how manufacturers will be able to continue to reduce nitrogen oxide and other emissions at the same time. After all, comparing today's exhaust with the dark clouds from older models, they've already made great strides. No one wanted to get specific about technical details, but industry insiders and observers cite any number of current and potential paths to cleaner engines. Among them are:

* new electronic controls that update all engine operating parameters faster;

* waste-gated turbochargers that maintain turbo boost under all conditions, thus defeating turbocharger lag;

* expanded use of devices such as catalytic converters;

* innovative fuel systems (Caterpillar says its new fuel system uses oil rather than a cam to drive the electronic unit injectors);

* spraying a chemical into the engine system to reduce nox (though it requires carrying an extra fluid); and

* exhaust gas recirculation mechanisms ("It keeps your fuel mileage where it needs to be while driving your emissions down," an industry rep says).

Another option for cleaner-burning engines is increasing the use of low-sulfur and additive-enriched fuels, though this option relies on the end-user's decision about what goes into the tank. Synthetic lubricants help as well, but that too is an end-user decision.

"We see diesel as a potentially 'green' fuel," Carso says. "Look at the United States gasoline fuel supply. It's probably the cleanest, highest-quality in the world. But our diesel supply is among the worst, particularly for sulfur content. It's probably 500 parts per million of sulfur. What we'd like to see is 50 parts per million to make it a high-quality fuel. It will be an important issue for manufacturers in the future."

Fire service implications Kloha cites the increasing use of electronic ignitions and electronic throttles as the primary current method to reduce emissions. For fire service leaders and their mechanics, reliability, serviceability and safety are paramount. All of these high-tech approaches are going to require careful testing and lots of communication between the fire service and the manufacturers.

"We're moving so fast in this field, it's hard for everyone to keep up," says Deputy Chief Gary Wolff, Lealman (Fla.) Fire & Rescue. "In California, they were talking about outlawing the diesel engine! They're trying to cut back on the air pollution, which is an admirable thing. But the manufacturers are going to have to work more with the fire department as they build these [cleaner] trucks."

Wolff says first-due firefighters will need very specific training as more emergency vehicle systems are controlled electronically. "If a computer shuts the engine down or kicks it back to idle, if the throttle on the pump panel doesn't function properly, what then?" he asks. "If something fails at the fireground, what is their backup? Some of the manufacturers have a manual override or another throttle in the cab area, but not all of them do. On the new ones, when you put it into pump gear, it cancels out the accelerator throttle."

Thorough field-testing of these new systems is vital, Wolff says, but he's not convinced enough of it has been completed to date, particularly in varying climates. Will all of these components work reliably in the bitter cold? How about in 100degrees-plus days with 100% humidity? "In Florida, we have problems with the streets flooding after heavy rain," Wolff says. "In one of our trucks, the air intake is too low - it sucks water into the air cleaner itself. We're also having a lot of the electronic transmissions fail now. They're overheating, losing power, and a lot of that has to do with the way it's been programmed."

All those electronic components can sneak up on you too. "Keeping your electrical system and batteries properly charged is really important," Wolff warns. "Instead of waiting three to five years to replace batteries on trucks, you may need to do it every two years to be on the safe side." Easy access to parts and qualified service technicians is another variable accompanying this high-tech revolution. "You have a frontline truck down for want of a computer chip," Wolff says. "Do you have to take your vehicle 30, 50, 100 miles to get a processor re-programmed?"

An alternative-fuel horizon These are all questions that will be answered soon enough. But what's on the farther horizon? Is there something waiting to take the diesel's place in fire service fleets?

Kloha says compressed natural gas could be a workable alternative fuel one day. He believes many fire departments could handle on-site fueling, and says current diesel engines can be modified to work with the fuel. Though it's certainly feasible, there are some logistic hurdles to jump first.

"Ethanol, compressed natural gas, liquid natural gas - granted, they're cleaner-burning engines, but the fueling systems they require are quite expensive," Berry says. "There's not fuel available on every corner. The delivery systems and the engine modifications plus the fuel tanks on the vehicle required to capture and hold the fuel have made those options cost-prohibitive."

Caterpillar has a diesel engine that burns natural gas in its dual-fuel system. "It puts natural gas into the cylinder with a quick spray of diesel to ignite it," a spokesman says. "A dual-fuel [system] is more than 90% efficient under heavy load as compared to a diesel engine."

Cummins has been selling a natural gas engine and a propane engine since 1989. "The size of tank storage is an issue," O'Brien says. "It's not just the vehicle; it's your whole infrastructure. Heating the apparatus bay with an open flame heater doesn't mix well with a lighter-than-air fuel source."

The 'why-take-gas-to-a-fire?' question arises, too - diesel fuel is less volatile than any of the proposed alternatives.

"Liquid natural gas is becoming a big thing with buses and mass transportation," Wolff says, "but it's a bulky system. We're trying to put the pump in the back [of the truck] to make room for firefighters and ems equipment. Buses have the storage system on the roofs, but where are we going to put that on a fire truck?" And, he asks, if a plain fire truck costs $200,000 now, what's the surcharge going to be for an alternative-fuel system?

All of the manufacturers say they're keeping up with advances in alternative fuels; some are working on the issue themselves. So will they ever replace diesel for heavy-duty applications? "I don't see that happening in the near future," Berry says. In a world that's still waiting for super powered bionic limbs, he's probably right.