A lot of people say that but has anyone actually tried it? Well last December, I decided that in the interests of scientific research I ought to try it. Faced with a flat battery in a Mini Cooper S I had the perfect opportunity. I moved the Lexus into position and left it in Ready mode. The engine was running because it was cold and I had the heater on. I lifted the bonnet and connected the jump leads which was a bit of a challenge on the Mini due to awkward access but I got a spark. I then jumped into the Mini, pressed the clutch pedal down and hit the start/stop button and it fired up straightaway. So I wouldn't say never, I would say take the same precautions as any other car i.e. don't ***** up the polarity, don't short the leads out and leave the Lexus in ready mode so that it can draw on the power from the traction battery if necessary.