I've recently aquired a new (to me) car, a 4 year old petrol driven VW Polo 1.4. My commute to and from work is (for the UK) quite long, about 400 miles a week, and several people have suggested that I'd be much better off with a diesel.

I'm no 'boy racer' so don't really care about any small (or even medium) drop in performance, but I do care about the overall cost, and more importantly about the environmental impact.

I've found (inevitably) lots of views on the web, but don't claim to understand many of them. For example, this page comments:

Overall, diesel cars emit less hydrocarbons, carbon monoxide and lead pollution than petrol cars, but produce more noxious gases and significantly more particulates....

...but doesn't tell me which is better for the planet.

I'd welcome any views on either the environmental or practical consequences of selling my petrol car and buying a diesel.

Many thanks,

Ed