The 2014 C class gets a new architecture, more rear seat room.Photo credit: CHRIS DOANE PHOTOGRAPHY

A bigger and roomier Mercedes-Benz C class will have a more dynamic exterior styling to challenge the BMW 3 series and the redesigned Audi A4 also due next year, sources told Automobilwoche, Automotive News Europe’s sibling publication.

The fourth-generation C-class sedan will debut at next year’s Detroit auto show and will go on sale next summer.

Spy photos suggest the C-class sedan will resemble the redesigned Mercedes S-class flagship that goes on sale in July in Germany.

The C-class will be based on a new rear-wheel-drive architecture and will grow about 127mm (5 inches) in length to 4699 mm (185 inches).

The added size mainly will increase rear seat room. Mercedes also wants to avoid cannibalizing the new front-wheel-drive CLA sedan, which began European sales in April and is close in size to the current C class.

The new C class will have three body styles in addition to the sedan. A coupe version is due in 2015 after debuting at the Geneva auto show that March. It likely will be called the CLK — a name Mercedes-Benz had dropped.

A convertible version will debut at the Frankfurt auto show in 2015 and will go on sale in early 2016. It will have a fabric top.

A station wagon will debut at the 2014 Paris auto show and will go on sale in Europe in late 2014.

The C-class will be built in Vance, Alabama, for North American markets. European production will be at Mercedes’ plant in Bremen Germany.