Diesel make-believe

SIR – Let’s not fool ourselves. People bought diesel cars (report, June 8) because of apparently high mileage per gallon and the low car tax. Few bought them purely to save the planet.

I have never owned a diesel car because it is obvious that diesel is dirty fuel. California long ago banned diesel cars because of particulate emissions. This was ignored by our government when introducing car tax based on CO2 output alone. We must now do something to reduce the number of diesel vehicles on our roads. Ray Page Nottingham

SIR – Production by diesels of many times more oxides of nitrogen and particulates than petrol engines has been known for years by anyone at all aware of the science involved.

Was their promotion yet another example of the failure of “group think”? Peter Crawford Sheffield, South Yorkshire