AN interesting press release landed in my inbox suggesting LPG was the best thing for the environment. I was intrigued.

I know LPG  (Liquefied Petroleum Gas) has had its moment in the sun, and its CO2 advantages have been whittled away by diesel. However, the price advantage at the pumps still very much remains in LPG’s favour (ask all those owners with converted LPG Range Rovers!) and I knew there were still some environmental advantages for the gaseous fuel.

But as the release came from Autogas and was a bit thin on why LPG was better, I thought I’d get in touch with the author of the independent report on which this release was based.

Dr Eric Johnson, the author of A comparative Environmental Impact Assessment of car-and-van fuels, is based in Zurich, Switzerland and works for Atlantic Consulting.

“A lot of people were asking how do modern cars compare, particularly in relation to Euro V and Euro VI emission regulations,” explained Eric. “So we tried to figure a comparison.”

Using independent emissions data that’s required for every car before it goes on sale in Germany, Eric and his team compared models that could run on a wide range of fuels – petrol, diesel, LPG bi-fuel, CNG (compressed natural gas) bi-fuel and CNG only – and were similar in size and power rating. They included the Ford Focus, Volkswagen Golf and Vauxhall Zafira.

They then analysed the exhaust emissions – carbon dioxide (CO2 – the gas used to calculate company car tax), carbon monoxide (CO), hydrocarbons (both methane and non-methane), nitrous oxide (NOx) and particulate matter (PMs) using the latest EU measuring systems – to ascertain which fuel had the most beneficial (ie least) impact on the environment.

Answer: LPG.