Petrol vs diesel – which fuel is cheapest in the long run?

I am planning to change my car in the next year and will have to decide on whether to stick with diesel or switch to petrol. My first diesel car was bought in 2002 when the main dealer was offering new Golf diesels at the same price as petrol models and the offer was too good to miss. My present diesel Golf was another new car that the dealer offered a good discount on, presumably to make way for new stock.

I would prefer to stick to diesel, but I drive only 7000 miles a year. What I buy will depend on what is on offer. I am not in any hurry to change my car and I will keep an eye on what is available from local dealers, whether that is petrol or diesel.

You’ve missed one essential consideration…depreciation. If you add up cost of ownership over a period, you’ll find that depreciation on anything but the oldest cars makes all other factors, including fuel costs, pretty insignificant for most drivers. (Insurance could be an even bigger hit for the young).

Most diesel cars depreciate more slowly than their petrol equivalents, reflecting their tendency to be longer-lived and (b) fuel cost is an even greater consideration for anyone buying an older car.

There are other things to take into account too, such as cost of servicing.

When replacing my car, I put together a simple spreadsheet to calculate cost of ownership of all the cars I’m considering. It includes factors such as cost of money (interest on a loan and/or loss of interest on capital), depreciation, road fund licence, insurance, servicing and fuel. The results are often surprising.

No matter what we the motorists plan..albeit petrol or diesel ;.the Government will swap about to keep that which makes most revenue for the Government. if people stop buying Diesel.the Government will bump up the petrol prices..if we continue to use diesel the price will increase..to maintain revenue…
the answer is get 20 petrol or diesel Customers and buy up a block stock of either….or maybe get 50 motorists to block reserve a stock at bulk prices from the Oil Companies….I’m sure that will beat the Tax man..

For many years diesel was significantly cheaper than petrol, then overnight Diesel suddenly became much more expensive.

I think we need to look at why this sudden change came about and why non commercial Diesel is so expensive. I think at the time the Govt said that drivers of Diesel cars were gaining by having a higher MPG and to have cheap fuel as well was too much of a good thing.

I have just purchased a small diesel car for my wife with the sole intention of running it on cooking oil, which is considerably cheaper.

You are falling into the trap that manufacturers want us to by quoting official fuel consumptions. The majority of motoring magazines do the same which makes their cost comparisons meaningless. In the real world official figures are pure fantasy. To use your example, I run a 1.6 diesel focus which has done 12,000 miles so is well run in yet even with gentle driving and 65mph cruising on motorways I only get 52mpg – nowhere near Ford’s claimed 67mpg. I prefer the superior pulling power of diesels but am seriously thinking of switching back to petrol but, for the reasons given above, i find it impossible to make any kind of true cost comparison.