Type the following below at any menu to activate the cheat. 

rushhour                Race with lots of traffic on the road
empire                  Race on the Empire City track
elnino                  Race with the El Nino car
merc                    Race with the Mercedes CLK GTR
gofast                  Make your car go super fast in Single Race mode
allcars                 Enable all cars including Pursuit Vehicles
jag                     Race with the Jaguar XJR-15 bonus car
dcop                    Gives you the pursuit Diablo SV bonus car
ecop                    Gives you the pursuit El Nino bonus car
monkey                  Gives you manual transmition with automatic 
                        functions
bullhorn                Cops use bullhorn when they pull you over 
                        (Hot Pursuit Mode only)
madland                 Removes all constraints from opponent AI. 
                        AI cars will drive at their maximum ability

Type the cheats below then click RACE to drive the different non-player cars. 

go01 - Miata
go02 - Toyota Landcruiser
go03 - Cargo Truck
go04 - BMW 5 Series
go05 - 71 Plymouth Cuda
go06 - Ford Pickup with Camper Shell
go07 - Jeep Cherokee
go08 - Ford Fullsize Van
go09 - 64/65 Mustang
go10 - ~66 Chevy Pickup
go11 - Range Rover
go12 - School bus
go13 - Taxi - Caprice Classic
go14 - Chevy Cargo Van
go15 - Volvo Station Wagon
go16 - Sedan
go17 - Crown Victoria Cop Car
go18 - Mitsubishi Eclipse Cop Car
go19 - Grand Am Cop Car
go20 - Range Rover Cop Car/Ranger Vehicle
go21 - Cargo Truck (same as 03)