In this segment from Motley Fool Investor Beat, analysts Jason Moser and David Hanson explain why they're keeping close watch on shares of CarMax (KMX -0.53%) and Nike (NKE -0.26%). With the average age of a vehicle on the road today in America up around 12 years, Jason sees CarMax as still having a lot to gain by consumers looking to replace their old vehicles affordably with used cars. Meanwhile, David will be watching when Nike reports earnings after market close today. While the company is world-class, Nike's valuation makes it a bit expensive today. David gives investors one metric he'll be watching for tonight with the sports apparel giant.