Work continues on the Mercedes C-Class Cabrio as another prototype has been spied undergoing testing.

Set to battle the Audi A5 and BMW 4-Series Convertible, the C-Class Cabrio has familiar styling but adopts door-mounted mirrors, a retractable roof and a revised rear end.

Our spies couldn't get close enough to snap interior photos but the cabin will likely echo the standard model.  However, we can expect an assortment of Cabrio-specific equipment including airscarf seats and new controls for the soft top.

Engine options will carryover from the sedan so expect an assortment of familiar petrol and diesel units including a turbocharged 2.0-liter four-cylinder with 241 bhp (179 kW) and a turbocharged 3.0-liter V6 with 329 bhp (245 kW).

Mercedes C-Class Cabrio spied once again