Thursday, November 08, 2007

Are Diesel and LPG 4x4s Better or Worse for our Cities?

We get a lot of complaints from disgruntled owners of large urban luxury 4x4s who drive diesel models or who have converted their old Landie to LPG.

Diesel cars in general burn 'hotter' and so are more 'fuel efficient'. They also emit less CO2. So, should we be congratulating drivers for 'going green' by buying diesel and using LPG?

Well, our friend Simon Birkett over at the Campaign for Clean Air has informed us that diesel engines should be replaced in general by petrol or LPG in cities and that diesel vehicles should be priced out of London. The reason? Diesel vehicles produce up to 3 times as much air pollution.

And while LPG generally produces less CO2 and other air pollutants than petrol models, the benefits aren't that clear cut. This week the Department for Transport released a report that compares petrol engines and LPG. The study shows that some car models produce twice as much NOx on LPG as they do with petrol. So, some vehicles are better and some are worse in this regard.

Also, the lack of refuelling stations for LPG means driving further may offset the inherent CO2 benefit.

Thinking about converting your vehicle to CNG (compressed natural gas)? It appears that it's not an alternative vehicle fuel to consider because it tends to leak and blow-up!