Art Spinella says environmental campaigners may be right about SUVs, but hybrids are an expensive part of the automotive picture. The vehicle at the top of his environmentally-friendly list is the Scion xB because it is easy to build, cheap to run and recycle, and carries a cost of 49 cents a mile over its lifetime. "I don't like the Hummer people using that as an example to justify the fact that they bought a Hummer," he said. "Just as it's not for Prius owners to necessarily believe that they're saving the entire globe, the environment for the entire world, that's not true either." In the June 2008 "From Dust to Dust" study, the Prius cost per lifetime-mile fell 23.5%, to $2.19 per lifetime mile, while the H3 cost rose 12.5%, to $2.33 per lifetime-mile. Actual results depend upon the distance driven during the vehicle's life. Greenhouse gas emissions Unmodified, SUVs emit 700 megatonnes of carbon dioxide per year, which causes global warming. Whereas SUVs can be electrified, their (manufacturing) emissions will always be larger than smaller electric cars. They can also be converted to run on a variety of alternative fuels, including hydrogen. That said, the vast majority of these vehicles are not converted to use alternative fuels. Weight and size The weight of a passenger vehicle has a direct statistical contribution to its driver fatality rate according to Informed for LIFE, more weight being beneficial (to the occupant). The length and especially width of large SUVs is controversial in urban areas. In areas with limited parking spaces, large SUV drivers have been criticized for parking in stalls marked for compact cars or that are too narrow for the width of larger vehicles. Critics have stated that this causes problems such as the loss of use of the adjacent space, reduced accessibility into the entry of an adjacent vehicle, blockage of driveway space, and damage inflicted, by the door, to adjacent vehicles. As a backlash against the alleged space consumption of SUVs, the city of Florence, has restricted access of SUVs to the center, and Paris and Vienna have debated banning them altogether. Despite common perceptions, SUVs often have equivalent or less interior storage space than wagons. While handling worse and burning more fuel due to high centre of gravity and weight respectively. Activism Siân Berry was a founder of the Alliance against Urban 4×4s, which began in Camden