GM's new engine to make its hybrids and plug-ins even more efficient

A 2007 Saturn Aura and Opel Vectra equipped with HCCI engine prototypes.

(Credit: GM)

GM announced its development of a new, more efficient internal combustion engine that will eventually be used to power its lineup of hybrid and extended-range plug-in vehicles.

In the homogenous charge compression ignition engine (HCCI), the air and fuel mixture is compressed to ignite rather than using a spark. When combined with other advanced technologies, the HCCI engine provides up to 15 percent better fuel economy, according to GM.

Its fuel savings are achieved from reduced pumping losses, burning fuel faster at lower temperatures and reducing the heat energy lost during the combustion process.

A prototype HCCI engine undergoing transient combustion

(Credit: GM)

This advancement is significant because it approaches the efficiency of a diesel but doesn't require the more expensive exhaust system required to meet California's and other "clean state" emissions standards. In other words, GM now has an engine that provides the fuel efficiency of a diesel but can be sold in all 50 states.

It will also play a key role in GM's ability to provide even better fuel economy in its fleet of hybrid and extended-range vehicles, which still require a diesel or gasoline engine to operate.

"We're working on a range of technologies, including vehicles powered by fuel cells, but in the mean time, we still need the internal combustion engine," says Susan Garavaglia, spokesperson for GM.

"We're not fully set up for plug-in electric vehicles or fuel cell vehicles. Until we get the infrastructure in place, we have to have a variety of solutions available. There will be some cities that can accommodate these new technologies, but for the rest of the public, we don't want to leave them stranded," she explained.

Further testing is still needed to ensure its stability in a range of operating climates, such as extreme temperatures and thinner air. Although she wouldn't disclose a firm date for competitive reasons, Garavaglia said it should be in production vehicles in "sooner than 10 years."