I get we are to see them interact and how they cope...... But by this point they know the weak spot, get the zombies in the head. They had a window cracked, why not use one of the arrows they showed in the car to brain scramble zombies until they could clear a path?
sharegood point...or perhaps start carving something into a stake that could be used to pierce them in the head.
shareElsewhere on here, one of the people involved in the film stated that with the passage of time it could be presumed that many things were tried in that time but not shown. (Edit: http://www.imdb.com/title/tt2272350/board/thread/224778849?d=224801470#224801470)
We also have to consider that, while easily piercing a zombie in the head makes for good zombie antics, the reality of the situation is that it takes anywhere from 16 and 196 psi to pierce a skull and that it's easier from the side than the front.
When you consider approximately 50 front facing zombies and not much leverage from within the car to get up to the amount of force you'd need to pierce the skull by hand, you'd also have to consider that, once you pierce the skull, it's a lot harder to remove the object because a vacuum is created and, again, there is a lack of leverage from within the car to use to your advantage.
Both good points Chancex74 however no one really knows the density of a zombie skull due to deterioration and decay, it may not be as hard as a regular human skull.
Thanks for pointing out the link of what the producer said, was a good read.
Cheers.