In 2012, the Sierra Club published a very nice toolkit called Employee Commuting: Best Practice. One of the sections covered employee shuttles, specifically mentioning Google Bus as a Best Practice.
However, the local San Francisco Chapter of the Sierra Club is apparently unaware of this. The group has come out against the use of employer shuttles — once again showing that a local group can take positions completely against the official policies of the national organization:
These companies offer as a perk to their employees living in San Francisco free transportation to and from their jobs. Meanwhile, the shuttle companies pay a revenue-neutral fee of $3.67 per stop per day to the San Francisco Municipal Transportation Agency. Tech companies get tax write-offs for providing free transportation to employees.
And yet, no environmental impact report has been done on this private transportation system with the potential for unlimited growth, unlimited interference with Muni, unlimited demographic disruption and unknown air quality impacts.
By all acccounts, the San Francisco tech shuttle program has been wildly successful. An SFMTA study found that 45% of riders did not own cars, and 45% of those cited the employer shuttle as the reason for not owning a car. Furthermore, 47% of riders said they would switch back to car commuting if the shuttle service were discontinued.