Mercedes-Benz has been spotted testing a prototype of the upcoming 2013 Mercedes-Benz CLC. The CLC will be a junior version of the larger CLS four-door coupe.

Rumours have been circulating for a while now that Mercedes-Benz is looking to introduce a smaller four-door coupe underneath the CLS, ready to compete with the likes of the Volkswagen Passat CC. These spy shots prove development is well underway.

Codenamed C117, the new CLC is based on the B-Class's MFA front-wheel drive platform, however, the layout does allow for all-wheel drive gearing to be added underneath.

Power is set to come from a range of petrol and diesel engines, including those seen in the new B-Class. This means a '180' and '200' petrol and CDI variants are likely. An AMG all-wheel drive version is also being rumoured, with a potential output of up to 250kW.

All versions will come with a seven-speed dual-clutch transmission, while a six-speed manual is also on the cards as a option for the diesel variants.

As for the styling, the new CLC is expected to showcase the company's latest design language, with large headlights, straight-cut lines and a somewhat conservative approach to trim shapes and contours. It will also feature a low and swoopy profile just like its bigger brother.

The Mercedes-Benz CLC is expected to be unveiled sometime in 2013. We'll keep you updated.