I stumbled across this today... http://news.bbc.co.uk/2/hi/health/8292089.stm I think the advantage is you take less notice of any noises from the car.. -- Dave G. KK7SS Richland, WA '06 Honda Civic Hybrid '65 MK III A-H Sprite '76 MKIV 1500 Midget Age is just another number... !