LPG fleets are helping reduce CO2 emissions by 111,000 tonnes, nitrous oxide emissions by 760 tonnes and particulates by 10 tonnes over a vehicle's lifetime, according to the Department for Transport.
Transport Minister David Jamieson said nearly 12,000 vehicles had received grant support for LPG conversions, totalling £13 million under the Government's PowerShift programme.
The figures refer to the total reduction in the emissions throughout the life of the vehicles compared with the conventional fuel equivalents.
Jamieson added: 'The support for the wider use of LPG vehicles is aimed at securing reductions in all these emissions to help improve air quality as well as reduce climate change emissions and the costs cannot be properly attributed to the CO2 reductions alone.'
He said there were 100,000 LPG vehicles on the roads in the UK, with most converted without a PowerShift grant.