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Chevy's Sequel is a prelude to the future

Given the absence of a conventional powertrain, I expected eerie quiet. But the noise level in General Motors' fuel-cell-powered Sequel experimental vehicle was not much different from that in any current luxury-level cross-over or SUV.

  • Choosing a car at dealership. Thoughtful grey hair man in formalwear leaning at the car and looking away

CAMP PENDLETON, CALIF.—Given the absence of a conventional powertrain, I expected eerie quiet. But the noise level in General Motors’ fuel-cell-powered Sequel experimental vehicle was not much different from that in any current luxury-level cross-over or SUV.

Not surprising, once I thought about it, since today’s conventional engines are so quiet that wind and road noise are the primary aural inputs in most vehicles. Replacing them with a fuel cell should make little difference.

Listening more carefully, I noted some unfamiliar, albeit subdued, sounds: electric-motor whine and forced air-flow to the fuel-cell stack, the engineers riding with me confirmed. And the sound-level rose and fell in direct proportion to vehicle speed, not to that of an engine speeding up and dropping back as gears shifted.

But I had to pay close attention to notice those differences. It is unlikely that a typical driver or passenger, who didn’t know this was a very special vehicle, would sense anything out of the norm.

And that is the point.

From a consumer perspective, this experimental Sequel — one of just two running versions in existence — could be sold today and, if competitively priced, would probably sell very well.

Unlike most other fuel-cell vehicles in trials around the world, the Sequel is not a variant of some existing model, modified to accommodate a fuel-cell propulsion system. It has been designed from the ground up around that powertrain and its auxiliaries, and it incorporates several other technologies and design features that the fuel cell enables.

To refresh your memory, the Sequel was introduced as a (non-running) concept vehicle at the 2005 Detroit auto show. It represented the third iteration of GM’s futuristic fuel-cell vision, which began with the AUTOnomy and was followed by the HyWire.

All three share the concept of a “skateboard” chassis architecture, introduced in the AUTOnomy, which houses the entire powertrain and running gear within a relatively thin under-structure that could be common to a variety of different body designs.

Key to that concept is the use of drive-by-wire technology, which relies solely on electrical connections between body and chassis for all control functions, including steering and braking.

My only steering complaint was a lack of a clear, on-centre feel — a characteristic that could be easily revised by changing the software, I was told. If I preferred the feel of a Cadillac Escalade, that could be arranged.

Ditto for the brake feel, which was beautifully linear and needed no fine-tuning at all, so far as I was concerned. That ability to tune both input and feedback characteristics by changing software is one of the major attractions of drive-by-wire technology.

It is even possible the same vehicle could encompass different programs to accommodate the preferences of different drivers within a family — for steering and braking feel and ride and handling characteristics, for example — just as vehicles can now remember seat adjustments and radio preferences.

At the heart of the Sequel, of course, is its fuel-cell powertrain, which includes an electronic control unit and a fourth-generation version of GM’s own fuel-cell stack — similar to the one used in 100 Equinox Fuel Cell vehicles to be built at GM Canada’s regional engineering centre in Oshawa next year for public trials.

Widely believed to be the way of the future, a fuel-cell is an electrochemical device that combines hydrogen fuel with oxygen from air to produce electricity. The only waste byproduct of that conversion is water vapour.

According to Byron McCormick, head of GM’s global fuel-cell development program, the design of the stack was frozen three years ago, to prepare for its limited-production. Developmentally, he says, the company is now two generations further on, with commensurate progress in size, cost and specific power output.

The Sequel’s fuel-cell stack has a rated power output of 73 kW (98 hp), supplemented by a lithium-ion battery pack rated at 65 kW. One 65 kW electric motor drives the front wheels and individual 25 kW wheel-motors (outboard of the rear brakes) drive each rear wheel, providing total tractive power of 115 kW.

That may not sound like much power, but electric motors have different characteristics than an internal-combustion engine. Specifically, they achieve maximum torque at start-up.

Consequently, according to GM’s figures, the Sequel will accelerate from 0-to-96 km/h in less than 10 seconds — quicker than a Hummer H3 and well within the CUV/SUV norm.

From behind the wheel, the Sequel portrays no muscle-car pretensions, but it does have right-now response, which imparts a feeling of confidence to the driver.

Hydrogen storage and, consequently, driving range are major challenges in the development of fuel-cell vehicles. The Sequel stores 8 kg of gaseous hydrogen in three cylindrical, carbon-composite fuel tanks, pressurized to 700 bar (10,000 p.s.i.) and mounted longitudinally in the skateboard, beneath the cabin floor.

That is sufficient to provide an unprecedented range of more than 480 km between fill-ups — in spite of the Sequel’s considerable 2,170-kilogram mass.

There is another factor, too. The Sequel is a big vehicle.

It is just short of five-metres long (4,994 mm), on an exceptionally long (3,040-mm) wheelbase — the better to accommodate those long fuel tanks. As a result, it is a very roomy vehicle, particularly in the rear seat.

As I said earlier, from a consumer perspective, it is a vehicle that could be sold right now.

GM has made no commitment to building the Sequel. But while he was at the drive program, GM vice-chairman Bob Lutz said he would push the company’s strategy board to approve full production of a fuel-cell vehicle as early as the 2011 model year.

According to McCormick, cost issues have now been addressed sufficiently that a fuel-cell system could be cost-competitive with current powertrains, “at volume” — interpreted to be 1 million units per year.

If the Sequel is a valid indicator, production fuel-cell vehicles may arrive far sooner than predicted by many industry watchers, including myself.


Gerry Malloy, a freelance writer (mgmalloy@aol.com), preapred this report based on travel provided by the auto maker.

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