The thing that Henry is tracking is; the effectiveness of his advert
We are told that henry purchased a sponsorship deal with his favorite NASCAR driver.
We are also told that his Company's Logo will be placed on the car. This means that it is a form of advertisement for his company
Now, since the car logo is a form of advertisement, if he watches every race to see how many times he can see his company's logo, it means he is tracking the effectiveness of his advert
Read more about advertisement at; https://brainly.com/question/25785890