The two questions are: should you buy a Tesla car (yes) and the second, should you buy TSLA stock (also a yes)!
For the latter, I look at market cap, product line, ability to deliver, future revenue opportunities, leadership/vision/intangibles (and balance sheets of course). Tesla makes a damn good looking car and they've only really made one (and they got into the NUMMI plant for a song). If you think they'll make more and better cars to more markets around the world and that they're just beginning and that their market cap of 16.7BB is low compared to Audi, GM, Ford, or Toyota, then you should buy their stock.
Telsa is limited by product line and production, not demand. That's a good position. My target for TSLA stock is $250.