I had this on the Coupe which is from the same period. I was driving home late night in the dark and the entire dash/headlamps/engine/powersteering went off with no warning. I have a brown interior, more so at that point in an auto in the outside lane of the A34. Only thing you don't mention is that it was raining and the windscreen was leaking like a sieve. I suspected water on the dashboard for steering column causing a short. In some cases the pipework to the windscreen washers can come loose (known fault and factory fix) and the water can be put through the dash causing it as well. Fill your windscreen wipers and run them to ensure they are all fully connected.
