GM Says It's Closer To Cleaner, More Fuel-Efficient Engine

General Motors Corp. (GM) said Wednesday it's getting closer to developing a new engine that would deliver diesel-like fuel economy with lower emissions.

The engine, called a homogeneous charge compression ignition or HCCI, could be a decade away and faces substantial challenges before truly becoming road ready.

But the cash-strapped auto maker needs all the help it can get on the fuel economy front. As of this week, GM faces added pressure of stepped-up federal fuel economy standards that promise to complicate the already daunting task of loading its fleet with gas-sipping technologies while slashing staff and spending.

"As the emissions standards continue to get tighter and tighter it is a challenge and it really will be a question of cost," said Paul Najt, group manager of group manager of GM's Powertrain Systems Research. "With this, we now have a system that is robust enough to put on the open road."

GM says the engine will deliver a 15% fuel economy improvement from a comparable engine on the road today. The auto maker has successfully tested engine in vehicles, but has yet to prove its durability over time or in extreme temperatures.

GM is competing against rival auto makers to bring the HCCI engines to market, most of which have various projects in the works. The engines are desirable because they provide much of the fuel efficiency of a diesel without the expensive aftertreatments required to get a diesel to meet emissions standards.

But auto makers have approached the technology with various levels of skepticism given the complexity of making sure the engine can stand up to stringent emissions, durability and cost demands. Volkswagen AG (VLKAY) and Toyota Motor Co. (TM) have each said they believe HCCI is a technology of the more distant future.

While the HCCI engine may be years away, a federal mandate to improve fuel efficiency is closing in. The Obama administration this week said it plans to order auto makers to increase the fuel economy of automobiles sold in the U.S. to 35.5 miles per gallon by 2016, four years faster than current law requires.

-By Sharon Terlep, Dow Jones Newswires; 248-204-5512; [e-mail]