We have recently purchased a new Mercedes-Benz E-Class Coupe CDI 250 together with SatNav as part of the option 50 package. This has proved to be frustratingly useless as it will only permit us to put in four digits of any postcode instead of the full six. We are directed well for 80 per cent of our journeys but the vital last part is not covered as the postcode is incomplete. When we asked our Mercedes-Benz dealer where we were going wrong, he replied that Mercedes-Benz makes its cars for the German market, which only has four digits in its postcodes. Why has the large export market been overlooked and what are the chances that Mercedes will one day issue an upgrade to cater for the UK postcodes?