Mary Barra's $280 billion goal confronts a litany of GM hurdles

(Bloomberg) -- Mary Barra's ambitious plan to double General Motors Co.'s revenue to $280 billion by the end of the decade has a relatively simple premise at its heart: Turn the legacy automaker into more of a tech company. Barra, the chief executive officer of one of the biggest carmakers in the US, is learning just how hard that pivot really is.

This…