Chevrolet Sequel Click to enlarge picture

The Chevrolet Sequel converts hydrogen to electricity through the fuel-cell stack, producing no harmful emissions—just traces of steam from the tailpipe.

That's the sound General Motors is hoping you will begin hearing from some of their sedans and wagons by as early as 2010.

The crossover SUV emitting the aberrant din was the Chevrolet Sequel, third in a trilogy of hydrogen fuel-cell concept vehicles built on GM's radical "skateboard" chassis, named for what it resembles.

Now all of GM's wizardry has been fashioned into a contemporary styled vehicle that you can drive to the grocery store, commute to work in or take on a driving vacation. What is perhaps most amazing is the pace of changes in GM's fuel-cell technology and vehicles in a relatively short period of time.

Chapters One and Two

First came the AUTOnomy concept vehicle reveled at the North American International Auto Show in January 2002. Underneath the wildly-designed two-seater body, a fuel cell propulsion system and three hydrogen fuel tanks were packaged neatly in the 6-inch thick skateboard platform. Engineered as an all-wheel-drive vehicle with an electric motor in each wheel hub, acceleration, steering and braking were electric "by wire"—no direct mechanical or hydraulic connections.

With the ability to easily change bodies, Larry Burns, GM's global head of research and development, boldly proclaimed that the automaker was going to "reinvent the automobile" with the AUTOnomy's fuel cell powered skateboard chassis.

Nine months later at the Paris Auto Show, GM took the wraps off the Hy-Wire, a drivable "proof-of-concept" vehicle. Its clean, futuristic shape, wide opening doors (no center pillar) and the motorcycle-like X-Drive steering and braking controls combined to make the Hy-Wire a worldwide media star for several weeks. While the Hy-Wire validated that different bodies could be mated to the skateboard and a by wire controlled fuel cell vehicle was drivable, it wasn't quite an AUTOnomy: The skateboard grew in thickness to 11 inches (more weight) and the vehicle was powered by a single electric motor up front (no A-WD). However, it proved to be an excellent test bed for the next chapter, the Sequel.

Don't Judge a Book by its Cover

Compared to the daring design of the AUTOnomy and 21st century look of the HY-Wire, the Sequel is, well, rather pedestrian in appearance. But that's been the plan all along.

The first two vehicles were all about getting attention by shouting, "Look at us, we're the future!" The Sequel, on the other hand, quietly says, "The future is now."

Indeed, the test Sequel seemed so much like a regular car, you could drive off a Chevy dealer's lot today, even though it was a prototype—one of two in the world that provided a real-world driving experience for a variety of media and others.

Where to Test a $1 Million Car?

With each Sequel costing somewhere close to $1 million, where in the world could GM release a herd of journalists for real-world driving and minimize the risk in their investment?

The 126,000-acre Camp Pendleton Marine Corps base along the Pacific Ocean about an hour north of San Diego was the ideal location. There's little chance of encountering cell phone-distracted drivers (forbidden on the base) and sparse traffic—think the middle of Wyoming.

Plus, chiseled, stern looks by Marine gendarmes at the guard shack were unspoken warnings for journalists to obey the base speed limits. Or else.

The 25-mile test route didn't seem like much of an opportunity to evaluate a million dollar wonder car, but it turned out to be a good microscopic sample of everyday driving: A four-corner intersection with typical suburban strip malls; a school zone; and smooth asphalt roads with hills, curves and a couple of mile-plus straight stretches—places to risk an encounter with Marine MPs and hit 20 over the posted 50 mph limit?

Wow, 2,929 Pound-Feet of Torque!

For all its white-hot technology and huge development costs, there's an air of arrant normality about the way the Sequel drives. Select "DRIVE" from the control panel on the center console, tickle the throttle and the Sequel zips off the line with an unexpected eagerness which belies its 4,774 pound curb weight.

A look at some figures explains why acceleration is remarkably lively. The electric motor powering the front wheels produces 1,740 pounds feet of torque. Each of the motors in the rear wheels produce 590 lbs.-ft. for an astonishing combined total of 2,920 lbs.-ft. of torque—all of which is delivered instantly by this all-wheel drive system.

When accelerating, the slight whine of the electric motors continuously increases without interruption of transmission shifts. That's because there is no transmission, the Sequel incorporates a direct drive design. Accelerator pedal, brake pedal and steering all act and "feel" remarkably similar to a normal car-based SUV, but that feeling is artificial. GM engineers have programmed the by wire driving controls to simulate driving feedback. And, in fact, the feedback can be personalized to meet different drivers' preferences.

When I commented to my front seat passenger, Dr. Mohsen Shabana, chief engineer for the Sequel, that the brake pedal had a somewhat soft, mushy feeling, he changed it to a more positive touch in about ten seconds with a few keystrokes on a laptop.

The steering is nicely weighted, but feedback is fairly numb. Despite the lack of a mechanical link, the car heads immediately to where you point it, thanks in part to its four-wheel steering capability. Should the primary and redundant steering systems fail, the car reverts to a mechanical steering backup. Like its driving manners, the interior also conforms to what is expected in today's crossover SUVs. An easily operated controller for audio, air conditioning and navigation is located to the driver's right on the center console—no reaching to the dashboard.

Under-the-Hood Moves to Under-the-Floor

Sequel is configured with seating for two in the rear and the cargo area can easily accommodate luggage for a family of four.

Nearly everything that makes the Sequel operate is out of sight. "With the skateboard chassis, under-the-hood moves to under-the-floor," said Chris Borroni-Bird, design and technology director at GM's Fusion Group.

Since the purpose of the Sequel's program was to make a real car with real-world driving capabilities, Borroni-Bird said the engineering design began with the hydrogen storage tanks. The three carbon composite high-pressure tanks store 8Kg of hydrogen pressurized to 10,000 psi, giving the Sequel the targeted 300 mile driving range.

The hydrogen is directed to a fuel cell propulsion module that consists of the fuel-cell stack, hydrogen and air processing subsystem, cooling system, and the high-voltage distribution system. Located under the driver's feet, it produces and sends 73 kW to the electric traction motors, enough output to deliver a 0 to 60 mph time of 10 seconds—quicker than some minivans.

And regardless of how quickly the Sequel accelerates, or regardless if it cruises at the top speed of 90 mph for miles, the process of converting the hydrogen to electricity through the fuel cell stack produces no harmful emissions, just traces of steam from the tailpipe.

Completing the propulsion system is a rectangular 65 kW lithium-ion high power battery pack under the rear seat area. The rear wheel hub motors serve a dual role as generators, capturing energy through regenerative braking to recharge the battery pack in the same manner as a hybrid vehicle.

And under the hood—yes there is a conventional hood that opens—is the Sequel's air conditioning unit. Borroni-Bird said it is similar to a home window unit that is simply plugged in.

Although the Sequel did not undergo crash tests, Borroni-Bird says computer simulation was used to validate all Federal safety requirements.

Final Chapter Not Finished

Why does GM continue to pour money into a program that is estimated to have already cost more than a billion dollars?

In Burns's words, the automaker wants to "take the automobile out of the environmental debate," a mantra that he and others at GM have been repeating for nearly 10 years.

An assessment of the Sequel says it lives up to the bold proclamation of having the potential to change the automobile as we know it. So, when will a version arrive that will be competitive in price to that of a conventional vehicle? In an interview, Larry Burns said the company is still committed to having a production-ready fuel cell vehicle by the 2010-2011 time frame, but emphasized that a go-ahead production date has not been finalized. "We have to have some assurance that fueling stations are available in a critical enough density to make sense for our customers."

When asked what type of vehicle it would be, Burns hedged a bit. "We haven't made that decision yet, there are a lot of options in play. What we do know is we want it to be something that is family oriented, that is a mainstream car opposed to something that is extreme."

As for a vehicle like the Sequel with a skateboard chassis and by-wire controls? It appears that the final chapter of "reinventing the automobile" is still being written.

Larry E. Hall is editor of Northwest Auto News Service and a freelance automotive journalist based in Olympia, Wash. He has an intense interest in future automotive technology.

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