A modern car can have as many as 200 on-board sensors, measuring everything from tyre pressure to windscreen temperature. A high-end Lexus contains 67 microprocessors, and even the world’s cheapest car, the Tata Nano, has a dozen. Voice-driven satellite navigation is routinely used by millions of people. Radar-equipped cruise control allows vehicles to adjust their speed automatically in traffic. Some cars can even park themselves. document.write(''); Once a purely mechanical device, the car is going digital. “Connected cars”, which sport links to navigation satellites and communications networks—and, before long, directly to other vehicles—could transform driving, preventing motorists from getting lost, stuck in traffic or involved in accidents. And connectivity can improve entertainment and productivity for both driver and passengers—an attractive proposition given that Americans, for example, spend 45 hours a month in their cars on average. There is also scope for new business models built around connected cars, from dynamic insurance and road pricing to car pooling and location-based advertising. “We can stop looking at a car as one system,” says Rahul Mangharam, an engineer at the University of Pennsylvania, “and look at it as a node in a network.”

The best known connected-car technology is satellite navigation, which uses the global-positioning system (GPS) in conjunction with a database of roads to provide directions and find points of interest. In America there were fewer than 3m navigational devices on the road in 2005, nearly half of which were built in to vehicles. But built-in systems tend to be expensive, are not extensible, and may quickly be out of date. So drivers have been taking matters into their own hands: of the more than 33m units on the road today, nearly 90% are portable, sitting on the dashboard or stuck to the windscreen.

Zipcar, the largest car-sharing scheme, shares 6,000 vehicles between 275,000 drivers in London and parts of North America—nearly half of all car-sharers worldwide. Its model depends on an assortment of in-car technology. “This is the first large-scale introduction of the connected car,” claims Scott Griffith, the firm’s chief executive