As long as the number of hummers is small, I don't think it's a problem. As more electric, heavy vehicles come on the road, road maintenance may not keep pace. A lot of county and rural roads have very low maintenance until heavy vehicles constantly drive up and down them. Regarding an electric bus, more people who might otherwise drive a shitty old car would ride in a bus if we're available. Each of those people isn't driving a 1-4 ton vehicle on the road. The net benefit of buses are greater than hummers. I doubt we'll adapt to electric cars fast enough anyways to avoid 3+ degrees of warming.