You are running late so you take the corner a bit faster than you ought to – but a disembodied voice on the dashboard is having none of it.

A new generation of in-car navigation systems will take sat nav from being simply an electronic mapping device to being a driving instructor, telling motorists when to change gear, at what speed to take a corner and even how to drive more economically.

The systems, due to be installed in cars within three years, will present detailed three-dimensional images of the road ahead showing obstructions, gradients and narrow stretches – potentially saving country lanes from the curse of misdirected lorries.

The systems will also be able to act as virtual tour guides, advising drivers where to turn off the road to find good restaurants or tucked-away country churches.

The Advanced Driver Assistance Systems (Adas), under development by leading sat nav manufacturers, will be a significant advance on the current devices which have become almost ubiquitous on dashboards over the past five years.

Fleets of vans with video cameras, global positioning systems and gyroscopes are now close to completing their filming of all Britain’s major roads and have started on smaller routes. This will enable the new sat navs to display buildings, bridges, traffic lights and road signs.

“The 3-D mapping taking place now will allow us to bring huge advances in the information that sat navs can provide for drivers,” said Rik Temmink, vice-president for global product management at Tele Atlas, the mapping division of TomTom, the market leader in sat navs.

Drivers’ uncritical reliance on their sat navs has led to a growing number of mishaps. Last year a woman wrecked her £96,000 Mercedes SL500 trying to drive across a swollen ford through the River Sence in Sheepy Magna, Leicestershire, after her sat nav told her it was a passable route.

The new systems are being developed by TomTom and Navteq, a mapping company owned by Nokia, the phone company which also produces sat nav systems. Early versions will be sold in shops, but carmakers such as BMW and Audi are cooperating in developing the systems and are expected to incorporate them in the dashboards of some new cars.

In addition to instructions on when to slow down or change gear for the best fuel economy, motorists will also be warned when they are driving erratically and will even be told at the end of the journey if they have caused undue stress to parts of the car.

To ensure that the machines are not simply bossy “backseat drivers”, the sat nav companies are also negotiating with producers of restaurant and tourist information to download information onto the 3-D maps.

DK Eyewitness Travel, which produces colourful tourist guides, is working with Navteq to supply restaurant reviews, hotel reservation numbers and guides to historic monuments. Drivers could be told, for example, that they were approaching Jane Austen’s old home in Chawton, Hampshire, and could ask for its opening times.

Sat nav makers are already introducing changes to improve their machines’ ability to “read” traffic conditions and communicate with other cars. Next month TomTom will launch a “live” service which tracks anonymously the locations of mobile phones in the pockets of millions of drivers, enabling the service to judge traffic speeds so that sat nav users can be warned of jams ahead.