Mazda Motor Corp. aims to boost average fuel efficiency 30 percent in the next seven years with new and reworked engines.

The company will upgrade almost all its gasoline engines by 2015 and roll out a stop-start idle system, a gasoline rotary engine and new diesel engines. Plans to trim 220 pounds from all new vehicles starting in 2011 will help Mazda achieve the goal.

Seita Kanai, Mazda's R&D chief, outlined the strategy.

He did not give an average fuel efficiency figure for Mazda's fleet, but the automaker already has improved fuel efficiency 30 percent since 2001, he said. More efficient engines will account for about two-thirds of the increased fuel efficiency.

Kia plans to release first coupe next year

Kia will get its first coupe when the replacement for the Spectra goes on sale next summer.

A version of the Koup Concept, shown at New York's auto show, will replace the compact Spectra, said Lee Hyun-soon, president of Hyundai-Kia Motors' R&D division. A sedan will go on sale by mid-2009, and the coupe will follow a couple of months later.

Chrysler overhauls its powertrains

Chrysler is rolling out its gasoline-electric Two Mode hybrid. Next comes a family of high-tech V-6s.

And in 2010, two powerful Cummins diesel engines will debut in the Dodge Ram and Jeep Grand Cherokee.

Read more about Chrysler's powertrains inside, N3.