The Double Decker is simply represented as a red bus with a flat, closed top, representing London's well-known red double-decker buses. Although unspecified in-game, the Double Decker is likely to be based on the Routemaster, which has been in use for 53 years since 1956.
The Double Decker's performance is actually poorer than that of the Coach in Grand Theft Auto 1, but exactly the same as the Coach and its open top variant in Grand Theft Auto: London 1969. Being the one of the heaviest vehicles in the game (the same weight as GTA 1 and GTA London 1969's Coaches and the Tour Bus), the bus is predictably slow, with a very poor top speed but average acceleration. The bus also possess below average grip and handling, and average braking. Although game files reveal the bus has a lucrative base export value of £1,000, the Double Decker cannot be exported due to its large size.