This is it, folks – this is your early petrolheaded Christmas present: BMW has released full details of the new BMW M3 Saloon and M4 Coupe. And we do mean full details. An output of 431 turbocharged horsepower is the headline, but really it’s the extent of the engineering overhaul carried out by BMW’s M division that really stuns the senses here. Both the M3 (blue car) and M4 (yellow car) go on sale in June 2014, priced at just over £56,000 – but for the time being let’s get geeky. These are such gloriously focused performance machines. The organisation hasn’t yet found the root cause of the problem – so it is working with fuel retailers to work out what’s causing it. It has its suspicions though: the 7% biofuel content that, by law, has to be added to diesel fuel. The issue concerns diesel fuel filters, which are becoming blocked by a gel-like substance in diesel. This starves the engine of fuel, causing it to either run on reduced power or not start at all. The orange engine warning light often also glows. This is similar to the old problem of diesel fuel ‘waxing’ in winter – but it’s not the same. Waxing has been cured by modern additives… and whereas waxed fuel used to clear when the weather warmed up, this problem doesn’t: the fuel filter has to be completely replaced. RAC patrols first noticed motorists were suffering from the issue last winter, but it disappeared over the summer. However, last month, when the cold weather returned, there were nearly 600 incidents! RAC technical director David Bizley said: “The industry is working extremely hard to find a solution… neither the fuel producers, nor retailers, nor the motor manufacturers saw this problem coming.