To be fair you also need to try and configure a Bentley or a Porsche and see what you end up with in extras.
Mulliner Driving Spec on a Bentley is £8.5K and comprises: "a choice of 3 standard veneers (Burr Walnut, Dark Stained Burr Walnut, Piano Black, drilled alloy sport foot-pedals, gear lever finished in knurled chrome and hide, diamond quilted hide to seat facings, doors and rear quarter panels; embroidered Bentley emblem to seat facings, 20 inch 2-piece alloy sports wheels (GTC)" Daylight robbery...
The problem is if you don't spec it, it makes the car virtually impossible to sell second-hand, as the Mulliner Spec also opens up the choice of body and leather colours, otherwise you're very limited in what you can have!
