There were howls of protest from motorists on Wednesday when it was disclosed that the Dutch firm TomTom, which is one of the world's leading suppliers of locational and navigation products, has indirectly been selling its Dutch customers' travel data to the police for years.

But others say the data can be used to improve traffic safety. A Dutch company, Via, buys the TomTom data, links it to information about speeding and traffic accidents, and it then sells the results to municipalities who can then take preventative measures.

The TomTom data also saves hundreds of thousands of euros because Dutch municipalities don't need to investigate complaints about speeding.