"Zombie Genocide Master" trophy hint
Have $2 million and the Driver magazine, which is located in BBQ Jacks near the soda fountain. Buy the SUV key from the pawnshop in Silver Strip. The SUV is located across the street in the Shamrock Casino. Drive it around the strip, killing zombies. The Driver magazine allows the SUV with to last three times longer. When your SUV is gone, enter a casino that forces the game to load, then back out and the SUV will have respawned in the Shamrock Casino, fully repaired. You can get about 4,000 zombie kills with each SUV spawn, requiring about fifteen minutes to get 72,000 kills.