IMDB Summary: After a confrontation with an unstable man at an intersection, a woman becomes the target of his rage.
The movie starts with a Crowe of the size of a Goodman attacking a couple with a hammer and then burning a house. After that, we switch for a family of a disorganized mother (Caren Pistorius), who just got fired and it is late to take her kid to school. In a traffic light, a truck -- later shown as being driven by Crowe -- doesn't move when the lights turn green, she presses the car horn too strongly, the guy on the truck gets pissed, gets no "I'm sorry" and decides to show what a "bad day" is. Then the chase starts.
... and that's basically it, and you can already figure out the end by the simple fact of how they shown Crowe as a bad guy and Pistorius as a bad-luck-mother.
What would be the main points of the movie, the chases in the streets, actually are very few and not that bad, accept that Crowe manages to create the worst case scenarios -- like a cop truck being smashed by a concrete truck -- out of pure luck -- or lack of luck for Pistorius, I don't know.
So you have the killings, which also seem like Crowe managed to think and plan all of them in advance, instead of being a spur of the moment. How? No idea.
Actually, the whole thing is weird. I mean, ok, there is the road rage, but what broke Crowe in such way that he would kill people to torment a woman because a honk? Why he burned the house in the very beginning of the movie? Nothing is said about this and he's shown simply as "bad guy".
While Crowe is still Crowe and delivers, the plot is too magical to actually make sense.