Bentley Mulsanne Key Celebrates Its Centenary Bentley's custom coachbuilding division, Mulliner, has designed a unique keycase to commemorate the brand's centennial. It's made of Dark stained Walnut with Piano Black Veneer and includes a flying "B" paperweight, keys, and an original 1930s booklet that features never-before-seen 1930s 8 Litre images.