2007 Chevrolet Volt Review

Specifications

In the past six months, General Motors has made some pretty hugedevelopments on the Chevrolet Volt. The little compact has not only been announced for production, but contracts for development of the internal systems have already been awarded. After such unexpectedly positive feedback to the very clever E-Flex series electrical powertrain, General Motors decided to do a second take on the Volt, but this time swapping out its little internal combustion engine for its brand new fifth-generation hydrogen fuel cell, which guarantees zero tailpipe emissions one-hundred percent of the time; a car that debuted this past April in Shanghai, China. This overview focuses on the changes between the original concept and the new hydrogen fuel cell version.

Both the initial Volt Extended Range Vehicle and Volt Fuel Cell share the same general construction. From the outside, the two cars look the same with their low-slung four-door three-box sedan shape, and ride on the same global compact car platform that’s shared with the Chevy Cobalt, Pontiac G5, HHR and the Astra. Both cars even use the E-Flex powertrain system, which features electric propulsion and a separateinternal combustion engine or fuel cell to charge the batteries. In other words, the engine or fuel cell doesn’t directly turn the wheels as it does in a conventional hybrid or for that matter a regular car. There are, however, differences in layout, powertrain and technology.

The key difference between the two models is that one features a fuel cell. GM’s RandD boffins have figured out a way to shrink the size of the fuel cell stacks by 30-percent while retaining the same power generating capabilities and power output ability (80 kW) as available with the fuel cell unit found in the fourth generation model. Essentially, the fuel cell is now small enough to fit into the same area as the initial ERV’s 1.0-liter three-cylinder turbo engine. The Volt ERV was designed with a single regular 120 kW electric motor that powers the front wheels, much like any other run of the mill compact car. The Volt Fuel Cell also has a single front-mounted electric motor, but it’s less powerful at 70 kW… and there’s more; the fuel cell version is actually all-wheel drive, featuring two in-wheel electric motors. The electricmotors that drive each of the rear wheels are 25 kW induction motors (think DC brushless) that provide 33.5 horsepower apiece. GM’s experience with previous fuel cell vehicles means that it’s no stranger to this technology. The compact design of the electric motors helped the engineers find space to locate the 9 pound hydrogen tank.

What’s even more exciting is that the use of two individual rear wheels allows GM’s engineers to essentially accomplish the electric equivalent of Acura’s Super-Handling All Wheel Drive system. Because the speed of the rear wheels can be controlled individually, the car can effectively prevent oversteer and understeer by speeding up (or overdriving) the outer rear wheel, while slowing down the inner rear wheel, reducing the effects of understeer. Who says that a hydrogen fuel cell car can’t be fun to drive?

Now, General Motors intends on making the Volt a true global product, and will produce the ERV and the fuel cell version for certain markets. For instance, Europe would receive the ERV model with a small diesel engine, while South America would receive the ERV model that could run on E85, or perhaps even E100 ethanol fuel. Which market would be the first toreceive the fuel cell version? Though it’s hard to say, the answer might be China, as it is currently working on developing a hydrogen refueling infrastructure, although we aren’t out of the question either given Governor Schwarzenegger’s push for the so-called Hydrogen Highway on the west coast by the end of the decade.

Another area of development that the Volt team is looking into is the charging system. Currently, it takes about six or so hours to charge the Volt’s battery off a standard 110-volt household outlet via the plug-in system, but they could soon find a quicker solution. Since the charging system is actually integrated into the car, it would be a matter of tweaking the system from 110 to 220-volts, which would speed up the charging time, not to mention the tweak could be done at a dealership. Another great charging solution would be for GM to revive the charging infrastructure it had in place during the EV1 years, albeit adapted for the Volt. This, of course, would only work for markets that sold the EV1.

One major concern for consumers and the hydrogen industry is safety, with hydrogen having been given a pretty bad rap for being highly flammable, but GM has done an excellent job ensuring that the Volt Fuel Cell isn’t an H-Bomb on wheels. The tank that contains the hydrogen is a plastic-envelope encased in 1.4 inches worth of ultra-rigid carbon filament (carbon fiber). Just how strong is this tank? Well, for starters it can withstand 50-caliber machine gun fire without puncturing, not to mention the guillotine test, which involves a very sharp blade being dropped 15 feet onto the tank. Naturally, it passes all the Government’s crash tests with flying colors. In the event of a hose failure or breakage of some sort, valves in the tank will automatically shut, cutting off the supply. Because of hydrogen’s composition, it will also diffuse into the air, away from the vehicle. So, in other words, as far as things go it’s just as safe if not safer than gasoline.

Having explored the potential of the E-Flex powertrain system with hydrogen, it looks as if General Motors is finally gaining momentum on a powertrain technology that will move us into the next few decades. Though no production dates have been scheduled for the Volt as of yet, things are looking good, and all RandD and testing is “on schedule”. We look forward to seeing and driving the Volt Fuel Cell when - not if - it is produced.