Dubai Police definitely the fastest in the world. Their fleet only the coolest supercars. Or rather (ready): Bugatti Veyron 16.4, Brabus B63S Widestar G-Wagen, McLaren 12C, Aston Martin One-77, Lamborghini Aventador, Audi R8, Ferrari FF, AMG SLS, Bentley Continental, Ford Mustang and Nissan GT-R. < br />
The total cost of all this stuff - 6, $ 5 million.
Source:
mirfactov.com/