According to this Businessweek article:
“…If necessary, the company would be willing to use a small gas engine to boost Blue Star’s range and broaden its appeal….”
That seems like an "about face" from Tesla's old stance of "all electric or bust".
A quote from one of Martin's Old blog entries:
"...Tesla Motors will remain focused on building the best electric cars for the foreseeable future. With each passing year, our driving range will get longer and the argument for plug-in hybrids will get weaker. To hell with gasoline..."