NY Times: Clean or Efficient? An Engine Goes for ‘Both of the Above’

FROM the outside, the dark blue Saturn Aura accelerating to a steady 50 miles an hour on the high-bank oval here at General Motors’ proving grounds looked altogether unremarkable.

In fact, it was not much to look at under the hood either, despite an experimental engine using a method of burning gasoline that may prove to be the next major advance in fuel economy and emissions control. Only a couple of stray electrical connectors hinted at the differences distinguishing this engineering prototype from thousands of other Auras on road.

You will see HCCI in diesels soon too. This process of combustion has been in the works in some form or another for quite some time.

The 2.2-liter engine in the test Aura is based on the G.M. Ecotec four-cylinder; a 2.4-liter version of this engine is available in the Aura for 2008. G.M. rates the H.C.C.I. engine at 180 horsepower and 170 pound-feet of torque of torque; by comparison, the ’08 Aura engine makes 164 horsepower and 159 pound-feet, and is rated at 22 miles a gallon in town and 30 on the highway.

G.M. would not give fuel economy figures for the H.C.C.I engine beyond the expectation of a 15 percent improvement in mileage.

so about 25 city and 34 highway and best inclass hp

be great for this type of engine to go into the volt too.

i bet the job they have is frustrating, but awesome too.