The chart below, which we are quite speechless to comment on, shows the market cap of TSLA, which will sell 35,000 cars in 2013 and must sell between 500,000 and 3,000,000 cars by 2022 to grow into its valuation (as explained before [5]), compared to some other car companies such as Fiat, Porsche, GM, Ford and Volkswagen. So yes: Tesla may be double the market cap of Fiat, but it is less than 20% the size of Volkswagen, so there is obviously much upside still.
[6]
And yes, we tried plotting the above market caps as a ratio to cars sold, but not matter what we did, we couldn't get the chart to be big enough.