General Motors unveils new details on its green strategy

[Mr. Wyndham]

Every automaker faces the same challenge, namely producing fuel-efficient vehicles that meet the most stringent environmental standards. The situation is particularly tricky in North America: gas prices are reaching new highs and environmental regulations like California's are tougher than ever.

"Oil needs are consistently rising, in large part because of emerging countries like China and India. If our calculations are correct, global fuel consumption will be 71-percent higher 20 years from now. Therefore, we need to quickly develop alternative technologies that will combine the benefits of combustion engines and electric drivetrains," explained Charlie Freese, Executive Director of Diesel Powertrain Engineering at General Motors.

With that in mind, hybrid vehicles will be at the forefront of GM's green strategy, which is likely to culminate with the introduction of the Chevrolet Volt and its E-Flex system. A recent tour of the automaker's laboratories allowed us to see how fast things are progressing.

Diversified strategy
Before going all electric, GM wants to diversify its operations by improving existing technologies and developing new ones. Despite doubts raised by Vice President Bob Lutz earlier this year, the company is leaning more and more toward diesel. "We realize that the North American market offers few avenues for small diesel-powered cars. Higher selling prices and higher fuel prices are making these cars less attractive and affordable. In fact, with a compact economy car, it might take you 400,000 miles to make any kind of profit," added Mr. Freese.

With larger, thirstier vehicles like full-size pickup trucks, however, a fuel economy of 15 mpg translates into a 75,000-mile break-even period.

Things are quite different in Europe, where diesel is cheaper than gasoline. So, GM will multiply its platforms and powertrains to reach consumers in every market. Overseas, GM dealers will soon offer a new 2.9L diesel V6 with the 2009 Cadillac CTS. This model won't make it to our shores, though.

Here, the green powertrain strategy will center around a new 4.5L Turbo Duramax engine for midsize and full-size trucks. This 310-hp mill boasting higher torque ratings should be able to meet California's emission standards.

Advanced technology
How is it possible? The new Duramax features high-tech systems to create less pollution. An advanced combustion process, known as homogeneous charge compression ignition (HCCI), not only provides significant fuel savings but also helps the engine meet current emission standards. It works with every combustion engine, including diesels.

Essentially, HCCI accelerates valve closing after the combustion so as to preserve a certain amount of heat energy. Air is directly injected through a central (not lateral) direct injection system before being compressed. Taking advantage of the hot air allows optimum temperature control. Once the right temperature has been reached (monitored by sensors inside each cylinder), gas ignition ensues.

The result is a steady, instantaneous and flameless release of energy throughout the entire combustion chamber, which eliminates all residues and ensures a cleaner combustion process.

"Even better, since we can spark an ignition at a lower temperature, we eliminate the entire production of NOx from our diesel engines and thus reduce toxic emission levels by 80 percent," said Mathias Alt, HCCI Program Manager.

Right now, HCCI is still in experimental stages. It can be found on two prototypes of Saturn Astra and Opel Vectra.

"HCCI and the emergence of new clean diesels are further proof that GM is going ahead with its green development strategy and focusing on technologies other than electricity and hydrogen. For us, the key is diversity," claimed Charlie Freese.

http://www.auto123.com/en/news/car-n...tid=97263&pg=2

[DGthe3]

good to hear