You may remember that last month I was left scratching my head by an ESP system that seemed to wink at me in the snow despite the ‘off’ button having been pressed. Well, the answer lurks on pages 5 to 15 of the owner’s manual: ‘The ESP system uses a Brake Limited Slip Differential function to improve vehicle traction. The BLSD system works when one of the driving wheels is spinning on a slippery surface. The BLSD system brakes the spinning wheel, which distributes the driving power to the other drive wheel… The BLSD system and ABS will still operate with the ESP system off. If the BLSD system is activated, the “SLIP” indicator light will blink and you may hear a clunk noise and/or feel a pulsation in the brake pedal.’

So there’s both a normal viscous LSD and BLSD. After donning safety spectacles and painting black and yellow quartered circles on my face I carried out various experiments to try and determine the parameters that would trigger BLSD with the ESP off. It was a lot of fun, but after multiple burnouts and lots of powersliding, I am none the wiser. In fact it very rarely triggered and when it did there seemed to be neither rhyme nor reason why. Answers on a postcard, please