Ride-hailing company Lyft is celebrating a milestone of sorts this week: It has now given 5,000 public rides in prototype self-driving vehicles operated by high-tech auto-industry supplier Aptiv PLC (NYSE:APTV).

Lyft was very late to join the self-driving technology rush, and its own research and development effort is still in early stages. But thanks to Aptiv and -- soon, perhaps -- other partners, some of Lyft's customers are getting a taste of the self-driving taxi experience. 

A white BMW with Aptiv and Lyft logos is shown on a Las Vegas street at night.

Aptiv's fleet of self-driving Lyft taxis has now racked up 5,000 paid rides in Las Vegas. Image source: Aptiv PLC.

A fleet of robot BMW taxis is operating in Vegas

This pilot program began earlier this year, when Aptiv deployed a fleet of 30 BMW sedans fitted with its prototype self-driving system in Las Vegas and made them available via Lyft's ride-hailing platform. 

Lyft customers who use the company's app to hail a ride in Las Vegas are given a prompt asking if they agree to ride in a self-driving vehicle. If the rider's destination is on a route approved for the self-driving vehicles, then they may get picked up by one of Aptiv's self-driving BMWs. Riders in the self-driving vehicles are charged Lyft's usual fares.

These vehicles are prototypes, meaning that they're not empty when they arrive to pick up a rider: The cars have human drivers ready to take control if the self-driving system begins to go awry. But so far, they've been well-received by Lyft customers in Vegas. The average passenger rating for a self-driving Lyft ride is 4.96 out of a possible 5 stars, the company said, and 96% of the passengers say that they intend to ride in a self-driving Lyft again. 

Who is Aptiv and how did it connect with Lyft?

Aptiv is the high-tech portion of former giant auto supplier Delphi Automotive, which split itself in two last year. The company has been working with Intel (NASDAQ:INTC) and Intel's machine-vision subsidiary Mobileye on a self-driving system that they hope to begin offering to automakers by the end of next year. In a parallel effort, the three have also been working with German automaker BMW AG (NASDAQOTH:BAMXF) on a series of systems for vehicles that BMW is aiming to begin producing in 2021. (It's no coincidence that Aptiv's self-driving Lyft vehicles are BMWs.) 

Delphi's self-driving effort got a big boost last October, when it acquired self-driving start-up nuTonomoy, a company formed by researchers from the Massachusetts Institute of Technology. A few months earlier, nuTonomy had signed a deal with Lyft to collaborate on a test of self-driving vehicles in Lyft service in Boston. (The nuTonomy team is part of Aptiv now.) 

Why Lyft is looking to Aptiv (and others) for self-driving

Lyft's own self-driving technology program is thought to be far behind that of its larger rival, Uber Technologies -- and even farther behind the companies generally cited as the self-driving leaders, Alphabet's (NASDAQ:GOOG) (NASDAQ:GOOGL) Waymo and General Motors' (NYSE:GM) Cruise. 

Waymo has already begun deploying its own self-driving taxi fleet, and Cruise is expected to follow within months. But while it works to catch up with the technology, it has come up with a workaround: Last year, it opened up its ride-hailing platform to a number of companies developing autonomous-vehicle systems, including nuTonomy, Ford Motor Company, and Jaguar Land Rover, which took a small stake in Lyft. 

A white BMW sedan with visible (but subtle) self-driving sensors and Lyft and Aptiv logos on its doors.

Note how well the self-driving sensors are integrated into this BMW. That level of integration suggests that this is a later-stage prototype. BMW has said that it plans to bring self-driving technology to market in 2021. Image source: Aptiv PLC.

What does it mean for investors interested in self-driving?

Self-driving vehicles have the potential to be a transformative technology, and the space has drawn tremendous interest from investors. But it's not easy to invest in "self-driving" right now. At the moment at least, there isn't really a "pure play" self-driving stock to buy. The closest thing we've seen so far was probably Mobileye -- but Intel acquired the company (at a hefty premium) early in 2017. 

That has left investors searching for the next-best opportunities. If you're one of those investors, Aptiv probably deserves a closer look. Revenue and earnings have both grown solidly this year, and the company has so far shown a knack for bolting on acquisitions that help advance its technology. 

And what of Lyft? If and when it goes public, Lyft is likely to show up on a lot of investors' take-a-closer-look lists. Much will depend on how well it stacks up against its more prominent rival, Uber, on many fronts -- including self-driving technology. But in its favor, Lyft has so far managed to put up good growth while avoiding the scandals that plagued Uber until last year. I suspect that it will have no trouble attracting interest -- and cash -- from investors. 

Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. John Rosevear owns shares of Ford and General Motors. The Motley Fool owns shares of and recommends Alphabet (A shares) and Alphabet (C shares). The Motley Fool recommends BMW and Ford. The Motley Fool has a disclosure policy.