Diesel vs Petrol - The Reality

The nation seems gripped by the thought that owning a diesel car automatically equals lower running costs. Whipped into a frenzy by Gordon Brown and his calculator, car buyers are happy to pay a premium for a diesel powered steer to save £35 on road tax. Has any one done the actual real life sums? or are the nation too lazy to think for themselves?

I decided to set about creating a hunble spreadsheet to see if the sums add up. In the absence of a spare Carol Vorderman I have done my best so you can keep your compaints to yourself :D

I choose two readily available cars from a popular manufacturer that had equivalant 3 year old models available for sale to enable a depreciation calcucation. The finance is based on decent deposit + 0% finance for simplicity. Petrol prices where taken as a national average from www.petrolprices.com on 28th May 2008.

Here are the figures for 10,000 miles per annum


and now 25000 miles per annum



So, with a BMW 320 at least, its only £226 cheaper to run than a petrol over 3 years!. I'd expect that rather meagre saving to be wiped out within 6 months as well as the price gulf between unleaded and diesel continues to grow. This largely unnoticed change in fuel prices over the last year has made it a close run thing between diesel and petrol for ecomony so make sure you do your sums before you buy that smokey tractor sound-alike. God they are awful!