It's not cheap, but the Mercedes E-Class Estate is classy and impressively refined. It's also generally comfortable, easy to drive, well equipped and a compelling option in the luxury estate car sector. Crucially, its boot beats the BMW 5 Series Touring's and Volvo V90's for luggage room, although the V90 does have more spacious rear seats. The E300de plug-in hybrid has the best fuel economy of any equivalent PHEV once the battery is depleted.