Dead Rising 2 - Zombie Genocide Master Achievement

Kill 72,000 zombies before to do this...you must buy SUV key from pawnshop at silverstrip(2M) after that.restart story(you can keep that key) at first,go to americana casino to get driving magazine(for time longer) this is route guide 1 round and go inside yucatan casino(nearest point) then get back to SUV (for respawn big zombies group and always new car) my achievement pop up around 7am of day4, good luck^^