The overhauled premises will have a new after sales centre on the opposite side of the carriageway, showroom capacity will be increased to eight models and their will be a new café and customer lounge.
"Both buildings will be much more in keeping with the Mercedes-Benz brand and will incorporate a host of new features - from an intricate lighting system that automatically adjusts with the sunlight to display cars at their optimum best to 'wi-fi hotspots' permitting internet use for visitors with laptops," said general manager Paul Smeeth.
As part of the redevelopment, Mercedes-Benz of Maidenhead's entire service department will be relocated to a dedicated workshop facility opposite the main showroom.
Maidenhead is the fourth major construction project to be undertaken by Greenoaks Mercedes-Benz in Berkshire. The group has already redeveloped its sites in Reading and Slough and is building new premises for its Ascot business.