DETROIT, Michigan — General Motors took aim at the youth market Monday, showing off sporty new designs for their smallest, entry-level cars at the Detroit auto show.

"At Chevrolet we believe we can capture the hearts and minds of these new consumers and become one of the brands, across all industries, that they truly love," said John McFarland, head of Chevrolet's global marketing.

"And we're doing this by going back to the core values of what Chevrolet has stood for over 100 years: passion, performance, affordability, and a youthful spirit."

Chevy's new subcompact Sonic is already selling well among the under-30 crowd and has helped boost grow the brand's share of young buyers by more than one percentage point over last year, GM said.

GM will soon expand its compact car offerings to include the Sonic RS -- available in a few months - and the Chevy Spark, which is selling well in Europe and Asia and will expand to include an all-electric model in 2013.

The two concept cars introduced in Detroit will further expand the brand's appeal, said Mark Reuss, president of GM's North American unit.

They are both four-seater coups which would come in around $20,000 and achieve 40 miles per gallon in fuel economy if they make it to market.

"The Tru 140S is what we call an affordable exotic, designed to look confident, expensive and fast," Reuss said.

"Code 130R represents pure functional muscle. It celebrates an era of real performance -- but without the retro feel."