DETROIT, Jan 10 (Reuters) - General Motors Co Chief Executive Officer Mary Barra said that although growth in the Chinese auto market has slowed, sales will grow significantly over the long term.

The world's biggest auto market "is going to be more volatile, but we still believe over the long term the market (will have) substantial growth," Barra told reporters at a Detroit auto show event on Sunday night.

The Chinese market is expected to show 3 percent growth in 2015, well below the double-digit gains it experienced earlier this decade. GM's sales in China rose 5 percent last year.

Last month, before the most recent stock market plunge in China, an industry association said auto sales were expected to rise 5 percent to 7 percent in 2016.

GM will begin this year exporting a compact crossover vehicle, the Buick Envision, from China. It is the first mass-market vehicle made in China that will be sold in the U.S. market.

Barra spoke after a Buick concept small sedan, the Avista, was unveiled. She said the car indicates the direction of Buick sedans, but would not say if there were plans to make a production model.

As Barra spoke, nearby was a new Buick Envision, a highlight for GM at the Detroit show.

She said that this year China sales of the Envision will be much higher than those for the U.S. market. Last year, GM sold about 147,000 Envision crossovers in China.

Karl Brauer, analyst at Kelley Blue Book, said the Envision is only the first of what will become a growing number of Chinese-made vehicles exported to the United States.

"Most consumers are not hung up on, if not completely oblivious to, where the car is made," Brauer said. "At the end of the day if it is a Buick-badged vehicle that we really like as a domestic buyer, we're going to buy it."

Joe Phillippi, head of AutoTrends Consulting, said the Envision hits right in the middle of the hottest-selling part of the U.S. market - small crossover vehicles.

"The Envision meets a need the (U.S.) Buick dealers have had for a very long time," said Phillippi.

The Envision goes on sale in the U.S. market in the second quarter.

(Reporting by Bernie Woodall; Editing by Bill Rigby)