"I'm sure that you're wondering, 'What good does walking on the track do?' That's a good question. When you're driving a race car, you get a lot of feedback about the track and the car. However, given the G-forces in play and the speed at which you're going, there are a lot of small details about the track that are very easy to miss. For example, let's say a turn is banked inward. As you're driving, you may not feel this. Because of your cornering inertia, your sense of 'up' is twisted so as to make the banking seem flat. However, knowing that the banking is there allows you to better judge the maximum turning speed through that corner, which you might not be able to guess looking at it through the windshield. There are countless other details to take in when walking the track. Another big one is the track texture itself, which plays a huge role in what you can do, and if it's raining, the fast line on the track can be 180 degrees off from where it is in the dry. Seeing the track's texture up close helps in judging where the fast line in under varying conditions."
Read the full story: Jack Roush Jr. Blog: Walk Slow to Drive Fast (Modified Mustangs & Fords)