How far in front of the car should a driver look when driving?

Most good drivers look at least 12 to 15 seconds ahead. That means looking ahead the distance you will travel in 12 to 15 seconds. At lower speeds, thats about one block. At highway speeds its about a quarter of a mile. If you are not looking that far ahead, you may have to stop too quickly or make quick lane changes. Looking 12 to 15 seconds ahead does not mean not paying attention to things that are closer. Good drivers shift their attention back and forth, near and far. [California Commercial Driver Handbook]