Just as truck operators start to use bio-diesel to be environmentally friendly, Friends of the Earth campaigns against them. It has launched an advertising campaign criticising bio-diesel saying:
"Biofuels are touted as being ‘green’ fuels, but the Government’s dash for biofuels could:

Destroy forests and valuable habitats.
Produce more greenhouse gases than they save.
Threaten the food supply and livelihoods of some of the worlds most vulnerable people.
Biofuels can be used in place of petrol and diesel. But they can only play a limited role in reducing greenhouse gas emissions.
So where does that leave truck operators wanting to go green? You could use the limited electric vehicles, but their is an enviromental cost in generating the electricity and heavy loss in transmitting it. And of course hydrogen fuel is, as always, 20 years ahead.

The best way to be environmentally friendly is to use as little fuel as possible. That way we can be green and add make more money. That is what I call a win/win, particularly in time of soaring fuel prices.