Petrol or diesel for large estate? I feel it is time to treat myself and will purchase either a Mercedes E-class estate or BMW 5-series Touring. Neither would be more than a year old, but I don't know whether to buy petrol or diesel. Being retired, I cover only about 10,000 miles a year and on that basis feel petrol is a wiser option. Salesmen all seem to suggest a diesel, so I wonder what you would do. If you can get it written into the purchase contract that you will never have any particulate filter problems, go for the diesel. If you can't, buy petrol. More than half the new cars sold in the UK are diesels, but 90 per cent are sold to fleet managers that dispose of them after three years or so, before the big trouble starts. If the British public starts to realise it is buying dud ex-fleet cars, the value of all used diesels will plummet. BMW DPFs tend to last 80,000-120,000 miles, then cost up to £2,000 to replace.