In the following video, analyst Brendan Byrnes speaks with Fool contributor Andrew Tonner about Tesla and the electric-vehicle market as a whole. Tesla has done a great job executing lately, and its stock has absolutely been on fire over the past few months, rising over 300% year to date. 

The Model S has proved to be a phenomenal car, but longer term, Brendan thinks that a lot of the success of the company will depend on Tesla's success in tapping the mass market for electric vehicles with a vehicle under $40,000 or so. 

Ultimately, this is not a company that Brendan is betting against right now, but at a $15 billion market cap, there's just not enough margin of safety in this stock for him to jump in. See the video for more details.

Fool contributor Andrew Tonner owns shares of Ford. Brendan Byrnes owns shares of Ford and General Motors. The Motley Fool recommends Ford, General Motors, and Tesla Motors and owns shares of Ford and Tesla Motors. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.