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Tesla's new Autopilot system made the biggest splash in 2015. But a lot of other self-driving efforts are gathering steam behind the scenes. Image source: Tesla Motors.

Self-driving cars are coming, we hear. But when? 

The answer is that fully self-driving cars that can handle all conditions without a human hand on the wheel are unlikely to come to market much before 2020 -- and maybe not for a few years after that. 

But a lot of progress toward that goal happened in 2015. Here are the high points.

Tesla joins the autonomous-car party
The biggest event of the year for self-driving technology was probably this: Upstart electric-car maker Tesla Motors (NASDAQ:TSLA) released the first iteration of its "Autopilot" system in October.

As it stands right now, Autopilot is pretty limited. It's probably best thought of as a very enhanced cruise control system. Like other advanced cruise control systems, it can keep your car at a set distance away from the car in front of it while cruising on the highway. But it can also change lanes (when told to), and steer the car to some extent. 

Mostly, though, it's much more aware of its surroundings than most existing driver-aid systems, thanks to its array of sensors and some very good software. And it's sending all that data back to Tesla, which will help the company develop more advanced systems over the next few years. 

The big guys are not far behind
Tesla's Autopilot is more advanced than anything else on the market right now. But that doesn't mean the big automakers are far behind. Giant auto-industry supplier Delphi (NYSE:DLPH) demonstrated its technology with an Audi prototype that (mostly) drove itself across the country back in March.

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Delphi's self-driving Audi prototype drove itself across the U.S. in March, with a little help from its human crew. Image source: Delphi.

Audi, part of giant Volkswagen Group (NASDAQOTH:VLKAY) is expected to bring a Delphi-based system to market in the next year or so. 

A lot of visible testing is happening across the industry
Audi has been testing its self-driving vehicles on public roads in California this year. But it's just one of several automakers busily testing self-driving car systems. Toyota (NYSE:TM) showed off its technology in a demonstration in Tokyo in October. It expects to bring its system to market around 2020 -- a date targeted by many of its rivals.

General Motors (NYSE:GM) is also well along with its system, which (for now, at least) it calls "Super Cruise." The first iteration of Super Cruise, which will focus on highway driving, is expected to come to market on the 2017 Cadillac CT6 in about a year. And Ford (NYSE:F) recently announced that it would begin testing its own system on public roads in California next year. 

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Ford is gearing up to test its self-driving prototypes in California next year, it says. Image source: Ford Motor Company.

GM's system uses the camera technology developed by Mobileye, which is widely regarded as the best in the world for self-driving vehicles. Tesla and Audi, among others, also use Mobileye's technology, and the company has partnered closely with Delphi.

Google and Apple are taking a different tack with autonomous cars
Google's self-driving car effort is about to get a new corporate home, under the Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL) corporate umbrella. Under the leadership of auto-biz veteran John Krafcik, hired earlier this year, Google's self-driving effort is said to be gearing up to to go to market -- as a car-sharing service.

Goog Self Driving Prototype May

Google's self-driving "koala" cars could evolve into an automated ride-sharing service before long. Image source: Alphabet.

Many in Silicon Valley (and elsewhere) believe that automated car-sharing services will eventually replace many or most privately owned vehicles, reducing traffic and the need for parking. 

We also learned earlier this year that Apple has put some effort into developing a car, presumably a self-driving one; some analysts (including your humble Fool) think that Apple is likely following a similar path, to a premium Apple car-sharing service rather than a mass-produced vehicle for sale to consumers. 

Will lawmakers get with the program?
Last but not least, lawmakers around the world are starting to think about self-driving cars. Not all of their thoughts are helpful to the technology, but some regulatory frameworks have begun to emerge. Most recently, just this past week, California announced that self-driving cars needed to have steering wheels and other standard controls, along with a licensed driver in the car ready to take the wheel during testing.

That was a blow to Google. The Googly One's prototype self-driving "koala" cars don't have steering wheels. 

John Rosevear owns shares of Apple, Ford, and General Motors. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), Apple, and Tesla Motors. The Motley Fool recommends Ford and General Motors. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.