The original 1971 version of this movie was beautifully vague about our hero Kowalski. He was a man trying to drive from Denver to San Fransisco to win a bet. Why was he willing to risk his life for the price of a handful of uppers? We're not really sure.
We had a few flashbacks that gave us the picture that he was an adrenaline junkie, and presumably he had led his entire life trying to make it to the vanishing point. That point you see off in the distance where the left and right shoulders of the road come together, and the road itself vanishes. He lives only to be free, and means no ill on anyone. We saw several times when there were accidents he stopped to make sure the other driver was okay before moving on, even the cops that were chasing him.
When he saw the futility of his quest he took his life rather than be arrested and live a life of captivity. He died like he lived, running wide open.
In the remake Kowalski has a whole history (including a first name, even.) He's trying to get to the hospital where his wife is suffering from complications to her pregnancy. He is a devoted husband, and excited expectant father. He comes to the decision to take his life after hearing his wife died in delivery, but they even leave THAT in question when they suggest that he may have jumped out of the car before it ran into the bulldozers. They even gave the part of "super soul," the blind DJ (brilliantly portrayed by Clevon Little in the original) to JASON PRIESTLY?!?!?!?!?!? Give me a break.