Where do you think wilson gets the information to track the car to gatsby?

Wilson learns from Tom that it's Gatsby who killed his wife. This is because Tom had driven Gatsby's car to New York, and ended up stopping at Wilson's for gas. To prevent himself from getting blamed, he said the yellow car belonged to Gatsby.

Wilson eventually goes to Gatsby's house, where he finds Gatsby lying on an air mattress in the pool, floating in the water and looking up at the sky. Wilson shoots Gatsby, killing him instantly, then shoots himself.