And hey, if you get tired of that you can use one of the new weapons to control cars remotely just by pointing it at them! Even better, halfway through the story the army is called in.
Doing it in front has you hijacking from the front. Yes, sprinting to the side of the car will have the player fucking dropkick the driver, sending said driver out the car through the other side. Why? Well, if you hold the button to hijack someone, you dropkick them out of the car.
It was revealed that Saints Row: The Third has a sprint button, but the company calls it the Awesome button.