When it comes to the used car market, I don’t pay much attention to the ‘official’ industry line on anything. Instead, I listen to you. And the burning question in the emails I’ve been getting lately is: “Should I buy diesel or petrol?”

This is an ongoing issue and won’t go away until there is an official answer via the fuel tax system. In the meantime, please let me make it clear that if you are buying a used car and don’t do that many miles - say, around 10,000 a year - then you might as well buy petrol.

Before I replied to a reader, I looked out of the window and noted that the four cars on my drive were all petrol, while the quite old one in the garage was also petrol-powered. I really don’t need diesel in my life and, depending on the circumstances, neither do you.

Now, I know that 85mpg is all very impressive, but you will have to spend a substantial amount of money to enjoy that level of fuel economy. Used cars don’t have to be dirt cheap, but the most singular appeal is that they dial out the most expensive motoring cost of all: depreciation.

The second biggest cost is fuel, unless you have a major engine breakdown, which will take you back to square one. So although you can get lucky with a high-mileage diesel, I get rather frightened by the associated particulate filters, turbos and dual-mass flywheel clutches, never mind all those injectors that have to be replaced.