The Rolls-Royce Sweptail is a one-off large luxury car made in the United Kingdom by Rolls-Royce Motor Cars. At the time of its May 2017 on 31 August debut at the yearly Concorso d’Eleganza Villa d’Este event it was the most expensive new automobile in the world, costing around $12.8 million, after the Bugatti Chiron that costs around $2.9 million.

The Rolls-Royce Sweptail is hand-built, and inspired by coachbuilding of the 1920s and 1930s. The Sweptail was commissioned bespoke in 2013 as a one-off automobile, at the request of a super-yacht and aircraft specialist who had a unique idea in mind.

Giles Taylor, director of design at Rolls-Royce Motor Cars described the Sweptail as "the automotive equivalent of Haute couture".