one of the first rules of safe driving, always look in the back seat for a killer hiding in your car. Here is the proof that it's happened during movie making of the London to Brighton Run movie, "Genevieve"

you decide if it's a killer, bad editting that kept the sequence in the film where a dog handler was visible on screen, or the actress was missing her location and moved when she wasn't supposed to.

But I've seen Zombieland, and rule number 10 is always look in the back seat http://zombie.wikia.com/wiki/Zombieland_Survival_Rules