Have you ever thought about taking a green driving test?

Here's a video of an environmentally-minded driver who took one. Proud of the fuel efficiency he gets from his own car, "how hard can it be?" Patrick Barkham asked as he set off. The challenge was to drive a Ford S-Max around an 8 mile circuit on one litre of petrol.

And the answer is in his case, was very hard indeed. Running out after 5 miles, he managed to achieve only 24 miles per gallon, 40% less than the ideal score. Over a year, that style of driving would emit an extra tonne of CO2.

As the green driving test shows, there could be a lot of scope for driver improvement, so aren't the carmakers right in insisting that eco-driving should be included in the CO2 emissions targets? It's all part of their "integrated approach" that demands that everyone needs to play their part in reducing CO2 emissions.

Eco-driving makes a lot of sense. No one is going to argue that changing your driving habits to make the most of the fuel in your car and limit your CO2 emissions is a bad thing. But to make that part of a target for carmakers to limit CO2 emissions on the vehicles they produce?

It would mean the carmakers can carry on churning out cars with higher CO2 emissions. Remember the EU target is 130g per km and the car lobby wants some of that to come from eco-innovations. So if 7g could come from something like Fiat's ecodrive system, just who is making the reductions?

It's up to you to make that 7g per km saving by driving more carefully. If you don’t your emissions are back up to 137g. So whatever you manage to save by eco-driving won't be an extra saving, it'll be you helping to bail out the car maker again.

And if you think that eco-driving is no problem and that Guardian report was fluke - here's another one in the Independent. He did even worse, only making it three miles around the course before he ran out of fuel.