How do you find out whether a rental car company is being eco-responsible or not?

You can check the website, of course - any rental company worth considering is going to have a page like this one for Avis UK. But how do you choose between them? One way is by doing a lot of Googling (Clare James for the Guardian found this out recently).

Or how about a car hire comparison service? We've just been made aware that VroomVroomVroom (great name) is opening a branch in the US, to complement its outlets in Canada, Australia, New Zealand and the UK. I did a dummy run on the UK site for a car at short notice here in York, and the results were impressive, covering the full spectrum of options from economy to luxury with details of car companies used, car model details and a pop-up photo of the vehicle in question.

So you can choose the car company that fits your principles. But there's more - because in association with Carbon Neutral, VroomVroomVroom will contribute towards green initiatives for every pound of carbon produced by a car booked through their service - at no extra cost. To kick the program off, they've already purchased 3,000 pounds of carbon offset credits. Eco responsible? Not half.

Image: Kyle May