SOME inventions, like some species, seem to make periodic leaps in progress. The car is one of them. Twenty-five years elapsed between Karl Benz beginning small-scale production of his original Motorwagen and the breakthrough, by Henry Ford and his engineers in 1913, that turned the car into the ubiquitous, mass-market item that has defined the modern urban landscape. By putting production of the Model T on moving assembly lines set into the floor of his factory in Detroit, Ford drastically cut the time needed to build it, and hence its cost. Thus began a revolution in personal mobility. Almost a billion cars now roll along the world’s highways.

Today the car seems poised for another burst of evolution. One way in which it is changing relates to its emissions. As emerging markets grow richer, legions of new consumers are clamouring for their first set of wheels. For the whole world to catch up with American levels of car ownership, the global fleet would have to quadruple. Even a fraction of that growth would present fearsome challenges, from congestion and the price of fuel to pollution and global warming.

Yet, as our special report this week argues, stricter regulations and smarter technology are making cars cleaner, more fuel-efficient and safer than ever before. China, its cities choked in smog, is following Europe in imposing curbs on emissions of noxious nitrogen oxides and fine soot particles.

Regulators in most big car markets are demanding deep cuts in the carbon dioxide emitted from car exhausts. And carmakers are being remarkably inventive in finding ways to comply.

Granted, battery-powered cars have disappointed. They remain expensive, lack range and are sometimes dirtier than they look—for example, if they run on electricity from coal-fired power stations. But car companies are investing heavily in other clean technologies. Future motorists will have a widening choice of super-efficient petrol and diesel cars, hybrids (which switch between batteries and an internal-combustion engine) and models that run on natural gas or hydrogen. As for the purely electric car, its time will doubtless come.


Towards the driverless, near-crashless car
 
 
Meanwhile, a variety of “driver assistance” technologies are appearing on new cars, which will not only take a lot of the stress out of driving in traffic but also prevent many accidents. More and more new cars can reverse-park, read traffic signs, maintain a safe distance in steady traffic and brake automatically to avoid crashes. Some carmakers are promising technology that detects pedestrians and cyclists, again overruling the driver and stopping the vehicle before it hits them. A number of firms, including Google, are busy trying to take driver assistance to its logical conclusion by creating cars that drive themselves to a chosen destination without a human at the controls. This is where it gets exciting.

Sergey Brin, a co-founder of Google, predicts that driverless cars will be ready for sale to customers within five years. That may be optimistic, but the prototypes that Google already uses to ferry its staff (and a recent visitor from The Economist) along Californian freeways are impressive. Google is seeking to offer the world a driverless car built from scratch, but it is more likely to evolve, and be accepted by drivers, in stages.

As sensors and assisted-driving software demonstrate their ability to cut accidents, regulators will move to make them compulsory for all new cars. Insurers are already pressing motorists to accept black boxes that measure how carefully they drive: these will provide a mass of data which is likely to show that putting the car on autopilot is often safer than driving it. Computers never drive drunk or while texting.

If and when cars go completely driverless—for those who want this—the benefits will be enormous. Google gave a taste by putting a blind man in a prototype and filming him being driven off to buy takeaway tacos. Huge numbers of elderly and disabled people could regain their personal mobility. The young will not have to pay crippling motor insurance, because their reckless hands and feet will no longer touch the wheel or the accelerator. The colossal toll of deaths and injuries from road accidents—1.2m killed a year worldwide, and 2m hospital visits a year in America alone—should tumble down, along with the costs to health systems and insurers.

Driverless cars should also ease congestion and save fuel. Computers brake faster than humans. And they can sense when cars ahead of them are braking. So driverless cars will be able to drive much closer to each other than humans safely can. On motorways they could form fuel-efficient “road trains”, gliding along in the slipstream of the vehicle in front. People who commute by car will gain hours each day to work, rest or read a newspaper.


Roadblocks ahead
 
 
Some carmakers think this vision of the future is (as Henry Ford once said of history) bunk. People will be too terrified to hurtle down the motorway in a vehicle they do not control: computers crash, don’t they? Carmakers whose self-driving technology is implicated in accidents might face ruinously expensive lawsuits, and be put off continuing to develop it.

Yet many people already travel, unwittingly, on planes and trains that no longer need human drivers. As with those technologies, the shift towards driverless cars is taking place gradually. The cars’ software will learn the tricks that humans use to avoid hazards: for example, braking when a ball bounces into the road, because a child may be chasing it. Google’s self-driving cars have already clocked up over 700,000km, more than many humans ever drive; and everything they learn will become available to every other car using the software. As for the liability issue, the law should be changed to make sure that when cases arise, the courts take into account the overall safety benefits of self-driving technology.

If the notion that the driverless car is round the corner sounds far-fetched, remember that TV and heavier-than-air flying machines once did, too. One day people may wonder why earlier generations ever entrusted machines as dangerous as cars to operators as fallible as humans.