GreenYour Air travel
greentomatocars (London, UK)
With a snazzy, informative website and a fleet of private hire hybrids, greentomatocars is the greenest ride in London (they'll also transport you to other points in the UK). What's more, the company offsets emissions by planting trees and partaking in various eco-friendly projects. Rates are comparable to or lower than non-green car services in London.