A GROUNDSWELL of support for bi-fuel vehicles has been provoked by predictions that the technology could be made obsolete by ultra-clean petrol and diesel engines in future. Manufacturers and fuel suppliers have hit back, arguing that alternative fuels such as LPG and CNG will always be one step ahead in terms of emissions performance.

In a vigorous defence of the benefits of bi-fuel vehicles, Vauxhall argue that LPG compared to petrol would save up to £459,538 on fuel costs for a 100-strong car fleet over three years/60,000 miles. It also refutes claims that investment in petrol or diesel technology would see emissions performance outweigh that of LPG or CNG.

Malcolm Noyle, manager of alternative fuel vehicles for Vauxhall, agreed that the refuelling network would eventually become large enough to move to single-fuel vehicles, but insisted that fleets had to see for themselves immediately the environmental and financial benefits of alternative fuels by using bi-fuel vehicles. 'There is a degree of compromise on emissions performance, but alternative fuel vehicles will always have better emissions than petrol or diesel counterparts.'

Jonathan Murray, manager of the Government's Powershift programme argued that LPG would always be cleaner than petrol and diesel, predominantly because LPG conversions are based on the latest petrol engines. Henry Clayton, motor gas development manager for Shell Gas, said: 'LPG vehicles produce a tenth of the emissions that a comparable diesel vehicle would do. Claiming bi-fuel fuel vehicles will become obsolete does not make sense.'