FLEETS have been warned that 'going for gas' does not automatically mean going 'green' unless they pick the right conversion equipment. Experts insist that emissions from vehicles running on liquefied petroleum gas will produce no benefits over traditional fuels if a sub-standard conversion is chosen.

Jonathan Murray, programme manager of the Government-funded Energy Saving Trust's Powershift project, said fleet managers should not be swayed simply by cheaper fuel bills from LPG - with savings of around 30p a litre available compared with petrol - but should only go for gas if they are determined to achieve tangible environmental benefits with a professionally installed, reliable system. He believes fleet managers recognise that alternative fuels have the potential to be clean, but are not looking at the technology which delivers that cleanliness.

'Our grants are meant as a carrot to encourage cleaner emissions and we are now looking at how we can target conversions which provide an obvious emissions reduction, which is critical to the programme,' he said. Powershift, which provides grants towards half the conversion costs, is investigating how to target grants at the cleanest conversions, rather than the current 'leap of faith' approach which assumes that all conversion kits work equally well.

Technological confirmation of the varying performance of conversion kits came from Clive Lawson, head of the vehicle emissions laboratories at Millbrook Proving Ground, who said fleets must learn to check the credentials of conversion suppliers and manufacturers. 'Just because you have chosen a clean fuel does not necessarily make your emissions clean. Calibrations of the engine have to be done correctly,' he said.