
Looking for a satellite navigation gadget? Watch out -- it may not work with your make of car. A growing number of vehicles are being made with athermic -- sometimes called solar -- windscreen glass. This type of glass has a thin layer of metal attached to it to block parts of the sunlight that heat a car up too much. Environmentalists like it because it reduces the need for air conditioning, thus saving energy. But sun rays are not the only thing the glass stymies. It knocks back lots of different kinds of radio signals, including those used by GPS satnav devices. I discovered this when trying to use Sony’s Nav-U50 in a Mercedes. (Not mine.) Other devices that have difficulty with the athermic windscreens are radar detectors and even mobile phone car kits. To get around this, luxury car makers are building satnav devices directly into the dash and wiring them to a small ‘shark-fin’ antenna on the roof of the car.
Cars built with athermic glass include new Renaults, Citroens, Peugeots, Vauxhalls, Audis, BMWs (X5s anyway) and some higher-end Mercs.