The geolocation system, designed by Marcus Brubaker and colleagues at the Toyota Technological Institute in Chicago, uses two simple cameras mounted on the car that survey its surroundings as the vehicle drives along. Software uses this camera data to work out when the road curves or is straight and then compares the layout of the route and its intersections to a map of the area from OpenStreetMap, a crowdsourced mapping application.
As the cameras pass by an increasing number of streets, the system eliminates the locations on the map that don't match up until it has worked out exactly where it is. On average, this process is completed after just 20 seconds of driving.
This method may sound too simplistic to work on the exact grids of a metropolis like New York, but according to Brubaker, it can pick up on the small differences in the size of each city block to pinpoint location accurately – even in Manhattan.
New Scientist (sub required)