Car horror stories involving sat-nav systems instructing drivers to navigate into rivers or worse are bad enough, but how about a navigation unit that take over your vehicle's brakes when it expects a stop sign?

The ' Navi Brake Assist' system from Toyota combines data from the GPS system and a rear-mounted camera to make the process as accurate as possible. It looks at road markings picked up by the camera and cross-references them with details on the locations of stop signs it expects to ensure accuracy.

Allow me, sir

Once it's sure there really is a sign ahead, it warns the driver with about 100m notice. When it gets a little closer, the auto driver kicks in and prepares to add its weight to the driver's foot on the brakes. The end result should, of course, be a guaranteed stop at just the right spot and fewer accidents.

For now, the system is on trial in four Japanese cities and only on wide roads with four or more lanes, although Toyota aims to expand coverage in the future.