Shares of electric-car pioneer Tesla (NASDAQ: TSLA) have rocketed higher by 65% since the beginning of December, after two and a half years of up-and-down performance. This big jump reflects growing anticipation for Tesla's upcoming Model 3 sedan, continued strong sales for its pricey Model S and Model X vehicles, and improving investor confidence regarding Tesla's other green energy ventures.Tesla's huge rally has boosted its market cap to about $49 billion, even though the company is still unprofitable.