WTF? I killed several zombies through first level and get 0 money in shop? Why?
Oh, I understand... I need to shoot zombies, not destroy them by my cool car.
But your Title - Zombie Truck, right?
Hm, I like to destroy them by car much more then shooting. It's so simple and cool and only arrows controls needed. More fun with less controls.
Music is ok, GUI not bad also (cool texts). Graphics can be better, poor animations.