There are VTA buses. They come every 30 minutes, and it would take you about 30 minutes to get to the Sunnyvale Caltrain station.
Walking would be just about as fast.
Apple operates door-to-door shuttles to SF and other population centers but that isn't really the point. The point is they have obviously provisioned enough parking to give each and every one of their employees a parking space, with some left over. It's just irresponsible given the traffic situation in the area, and to call it energy efficient is greenwashing.