Chrysler is kicking off production of the Chrysler 200 and Dodge Avenger sedans, two revamped cars that are critical to the automaker’s future.

Chrysler CEO Sergio Marchionne visited the Michigan plant where the cars are made Monday. He said the company has spent $300 million revamping the two mid-size cars, giving them new engine options, a new look and other features. The company needs to attract buyers who have been shopping elsewhere in recent years as Chrysler struggled through bankruptcy.

The Chrysler 200 replaces the Sebring sedan, which had been maligned for its poor handling and cheap interior.

The sedans will help Chrysler compete in the mid-size car segment, which is one of the largest and most competitive segments in the U.S.