Note that the "defeat the boss 20 times for grand prize" is a lie.
Edit: Defeat Mayor Turnball 20 times to receive the ECPD Riot Gear (540/832).
Defeat Mayor Turnball 30 times to receive the Weekend Ride (2515/2059).
Defeat Mayor Turnball 50 times to receive the Mayor's Revenge (5202/2802).
Previous three screenshots courtesy of c00guy.