The results of an Accenture study published in Fast Company [2]shows that world-wide consumers are willing to purchase significantly more expensive green cars if they are superior in every possible way than a gasoline powered vehicle.
Links:
[1] http://www.library.northwestern.edu/libraries-collections/evanston-campus/transportation-library
[2] http://www.fastcompany.com/1575905/study-consumers-only-want-green-cars-if-they-are-superior-in-every-possible-way