How the Cadillac Provoq Works

The Cadillac Provoq is powered by a hydrogen fuel cell that sits under the hood, right where you'd find the engine in a typical car. Inside the fuel cell is the stack -- a sandwich of anodes, cathodes and other high-tech materials -- that enables a chemical reaction to give the Provoq its power. At the back end of the vehicle, below the cargo floor, two storage tanks hold 13.2 pounds (5.99 Kg) of hydrogen gas at 10,000 psi. The hydrogen is fed to the fuel cell and mixed with oxygen, which is drawn from the air, pressurized and humidified. The fuel cell can constantly crank out 88 kW of power, which is equal to about

118 horsepower.

Running along the center of the chassis, beneath the floor of the vehicle, is a series of lithium-ion batteries. These batteries can be charged by plugging the Provoq into an electrical outlet through either of the front fender ports. The battery power can be used to extend the Provoq's range, or it can give the motors a little extra juice if they need to accelerate quickly. The batteries store a maximum of 9 kWh of energy and can generate a peak of 60 kW (80.5 horsepower) for a power boost.

The Provoq is an all-wheel-drive vehicle, giving it stability and traction in a wide range of conditions; however, it doesn't work like most other all-wheel drive vehicles. Instead of a transmission that sends the engine's power to each wheel, the Provoq makes use of three separate drive motors. One motor provides drive for both front wheels at 70 kW (93.9 horsepower). Each rear wheel has its own hub motor, providing 40 kW (53.6 horsepower) of driving force. With that power, the Provoq posts a 0 to 60 mph time of 8.5 seconds and has a top speed of 100 mph. At first, that may seem unimpressive compared to the muscle-bound concept cars of recent years, but they're good numbers for a fuel cell vehicle. Also, electric motors are able to deliver strong, instant torque to the wheels, which makes for very responsive acceleration.

Just how environmentally responsible is the Cadillac Provoq? Does the eco-friendly part of this concept start and stop with the fuel cell? What other green features does the Provoq offer potential owners? Find out on the next page.

General Motors claims the Provoq can drive 300 miles before the hydrogen tanks must be refilled. The last 20 miles of the trip come from the range-extending ability of the batteries, so aggressive drivers might not get as far. While the logistics of making, transporting and storing hydrogen mean that fuel cells are not totally without an environmental footprint, a car that doesn't release a single whiff of carbon dioxide is certainly a breath of fresh air. Currently, hydrogen is produced using natural gas (methane). There is low demand for hydrogen, and the price is tied to the cost of natural gas. If fuel cell vehicles become common, demand, along with prices, will rise. There are ways to make hydrogen without using methane, but they obviously require energy. The actual "greenness" of the Provoq and other fuel cell vehicles will depend on the power sources used to make the hydrogen.

The Provoq's environmentally friendly credentials aren't just about clean emissions and alternative fuels. GM has built several other green features into the concept. Part of the roof is taken up by a solar panel that draws in the Sun's energy to power accessories like the stereo, interior lights and the integrated hard drive. The tires were custom made by Michelin and use that company's Green-X technology. Although the tires maintain performance and grip, they also offer low rolling resistance. That means the motors don't need to use as much energy to turn the wheels, improving the overall efficiency of the Provoq.

GM touted several other eco-friendly features in their press release for the Provoq:

You can charge up the Provoq's batteries overnight by plugging either of the front fender charging ports into an outlet. No external charging device is necessary. The charging ports are part of the Provoq's sleek design -- instead of hiding them away behind a panel, GM's design team integrated them into the sweeping shape of the side panels. An amber light shows that the batteries are charging, and a green light indicates a full charge.

You're probably guessing that the new technology and eco-friendly design compromises the comfort and luxury that you've come to expect from Cadillac, right? Don't be so sure. Continue reading to find out how the Provoq is still very much a Cadillac.

The four-door Provoq is either a small SUV or a sporty wagon, a class of car currently known as a crossover. One of the original design parameters of the Provoq was that the alternative fuel system couldn't intrude on the interior space. With the low, center mounted batteries -- which also give the Provoq a low center of gravity -- and the fuel cell stack mounted in the engine compartment, that mission is mostly accomplished. Even when compressed, hydrogen is not as dense as gasoline, so the hydrogen tanks take up a certain amount of space. Even so, there's still room for a decent-sized rear cargo area and 60/40 split folding rear seat.

Being environmentally conscious about your vehicle choice can sometimes mean that you're willing to sacrifice some of the interior refinements that you would typically find in a luxury car. Not so in the Cadillac Provoq. In fact, it offers superfluous touches like "hand-wrapped leather with French seams" on the seats; ambient lighting on the door panels, footwells, sills and even beneath the seats; and USB ports for all your electronic devices. You can also put your cell phone into the cell phone holder, which is Bluetooth-ready and capable of inductive charging. No need to bring your iPod along -- the hard drive can store thousands of songs and maps for the navigation system. The instrument cluster has configurable LCD displays, while the center stack has the controls for the air conditioning and heat plus the

audio system.

To keep the ride comfortable, the Provoq sits on a four-wheel independent suspension, with Macpherson struts in the front and a four-link system in the rear. Neither is an especially revolutionary suspension, but the Provoq isn't meant for high-speed cornering at Laguna Seca. There are no hydraulic brake lines -- the Provoq uses a brake-by-wire system. This means the brakes are electronic. Each stop the vehicle makes will extend the Provoq's range slightly, as the regenerative brakes recharge the batteries.

It may take a while to get your hands on a new Cadillac Provoq. General Motors has no immediate plans to make a production model, and no pricing estimates have been given.

To find out more about fuel cells, hydrogen and concept cars, follow the links on the next page. They'll provide you with a lot more information.