I intend to change my 2001 BMW 530i Touring (73,000 miles) for either an Audi A6 or Mercedes-Benz E-Class estate. I have always driven petrol-engined cars and since I don't do a lot of miles the extra fuel cost is not a big issue. The problem is that there are very few petrol models available as a two-year-old used car, despite the improvement in fuel economy over the past few years. I guess this problem is created by sales people in the motor trade telling their customers they must buy diesel almost irrespective of annual mileage. I read in your column that more and more diesels are suffering from problems with their particulate filters because of low mileage, so what is a low mileage user to do? My regular commute to the office is six miles each way and my total annual mileage is less than 8000. Would that be a problem in a modern diesel?