Key TakeawaysNeedham analysts upgraded Carvana stock to "buy" from "hold," calling the company a "secular growth story."The company introduced a new feature that automatically applies federal electric vehicle (EV) tax credits at checkout.Carvana shares continued to rise, adding more than 5% in intraday trading Wednesday. Carvana (CVNA) shares sped higher Wednesday after analysts at Needham upgraded its stock and the company unveiled new features for buying electric vehicles (EVs). The digtal car-buying comp ...