FOR many visitors to the 1938 New York World’s Fair, the highlight of their day was General Motors' pavilion. There they could see and hear how some day motorists would be able to simply type in a destination, settle back, and read the morning paper on the way to the office, without needing to drive the car themselves. After 70-odd years, GM may be just about to deliver on that promise.

On September 7th the carmaker's boss, Mary Barra, announced that the carmaker’s Cadillac division will launch its new semi-autonomous Super Drive system in 2017. Though a motorist will not yet be able to go places while snoozing on the back seat, the system would permit hands-free highway travel; human control would only be needed when it is time to refuel or exit onto a local road. Cadillac also plans to introduce a new vehicle-to-vehicle communications system on one of its mid-range models. That will allow the cars to “talk” to one another, passing on information such as weather conditions and traffic problems, as well as help avoid collisions. “No other suite of technologies offers so much potential for good, and it’s time to turn potential into reality,” Ms Barra said during a speech at the annual Intelligent Transportation Systems (ITS) World Congress in Detroit earlier this month.

Until just few years ago, this all still seemed the stuff of science-fiction films. But autonomous-vehicle technology is advancing so rapidly that manufacturers and automotive suppliers alike are racing to see who can be first to develop a commercially-viable self-driving car. Last year Nissan, a Japanese carmaker, said it planned to have a fully-autonomous vehicle on the road by 2020. Google is already experimenting with a fleet of 100 self-driving prototypes, some of which will do away with pedals and steering wheels entirely, leaving only an emergency-stop button within the occupants' reach. A desire for a strong foothold in automomous driving seems to have been the motivation for a $13.5 billion bid this week by ZF Friedrichshafen, a German car-parts maker, for TRW Automotive, an American firm whose products include video and radar systems for cars.

But whether the industry will be able to deliver on time remains to be seen. Even Chris Urmson, the head of Google’s autonomous-vehicle programme, acknowledges that there are challenges still to be overcome. Some of these are technical in nature. Considering the record number of safety-related recalls announced in America this year, self-driving cars will need to prove themselves to be fault proof. Smart cars also will need to understand not only the basic rules of the road but how to react when human drivers do not do what they are supposed to. Cost is yet another concern. Autonomous vehicles will need cameras, radar, laser and sonar sensors that could add thousands of dollars to their price tag—though, as with the latest smartphones, the costs of these technologies are plunging.

Realistically, most experts believe that self-driving vehicles will be phased in a step at a time. A variety of models can already park themselves, and some Mercedes, Acura and Infiniti cars are now able to hold their place in a well-marked lane if the driver turns away for a few seconds. Nissan plans to roll out several more sophisticated “near-autonomous” technologies before the end of the decade.

To support this push, a number of countries are setting up vehicle-to-infrastructure systems, such as the new pilot project announced at the ITS meeting, which will cover 120 miles of roads around Detroit. As with vehicle-to-vehicle technologies, drivers would be able to track traffic and weather problems and get warnings suggesting possible diversions. By linking vehicles and highways together, one possible payoff would be a concept known as “platooning,” which involves driving cars almost bumper-to-bumper. This can help cut congestion, raise fuel efficiency, and help traffic to steer clear of crashes and other problems.

However, for all the optimism at the ITS conference, there are concerns that the technology could be hacked by criminals, as have other smart devices, such as fridges and toasters. The National Highway Traffic Safety Administration, a quango, has already warned the industry that it must prepare a response to computer hackers, who are increasingly turning their attention to smart cars. That not only raises the possibility that cars could be stolen with the help of their self-driving systems, but that they could also be hijacked remotely, with their owners on board. Some congressmen have also questioned whether the data collected by these sorts of vehicles could be used for nefarious ends by big business or government.

Despite such concerns, few expect the era of autonomous driving to be delayed. A recent forecast by Navigant Research, a consulting firm, predicted that as many as 95m self-driving cars a year could be sold by 2035—with virtually every vehicle sold worldwide featuring at least some basic version of the technology. Seven decades after GM predicted that one day cars would be able to drive themselves, its vision is finally starting to turn into reality.