Cars from Google spin-off Waymohave logged 20 million miles. Russia's Yandexand China's Baiduhave programmed cars to stop at streetlights, yield to pedestrians, and pass slow vehicles.

But these companies don’t build their own cars. Instead, most of them rely on a few popular models with easy-to-hack computer and infotainment systems that don’t require a lot of retrofitting. The cars might have different logos and sensors on them, but underneath, they’re the same. So what cars are self-driving companies using?

Lincoln MKZ

Qualcomm is building an advanced driving system that is basically autonomous, but still keeps the human driver in charge. The chipmaker is focused on giving car companies a "plug-and-play supported platform." That means a carmaker can pick and choose what tools and features they want built into the car, from warning systems to fully automated highway driving.

Qualcomm's test car for its Snapdragon Automotive third-generation processor is a Lincoln MKZ sedan.

"It's an easily available vehicle to get started," Anshuman Saxena, Qualcomm senior director for autonomous and advanced driving systems, told me before a demo ride in Las Vegas.

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Qualcomm outfitted its MKZ with a new computer system, eight cameras, six radar sensors, and more. It's not the only company that uses the Lincoln sedan. So does Amazon-backed Aurora, which outfitted a small fleet of the cars with LiDAR light-measuring sensors, cameras, and radar.

The Aurora Driver is part of a strategy to build a system that can transform any vehicle into a self-driving machine. The company already has the Driver on seven platforms like the passenger sedans I rode in, but also cargo vans, semis, and heavy-duty trucks.

Chrysler Pacifica

At this point, Alphabet's Waymo has become synonymous with the Chrysler Pacifica minivan. The vehicles in its Waymo One taxi service, which is available in the Phoenix area, are fully driverless, with nobody, not even a safety operator, in the front seats.

Why the Pacifica? It features a robust sensor system to detect other cars and pedestrians, along with a strong automated driving system with parking assist and active braking. Hybrid versions are appealing because they make "refueling" a fleet easier, since you don't need to rely entirely on gas stations. Waymo outfits its taxis with LiDAR sensors, cameras, and radar equipment.

Inside, the Waymo Pacifica looks like any other minivan, save for some extra screens and wires.

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Lyft is currently offering self-driving rides with Aptiv in Las Vegas, but its own Level 5 autonomous car research division is stocked with sensor-loaded Ford Fusions. The next addition to the fleet? Chrysler Pacificas.

In a November blog post, Lyft autonomous driving head Luc Vincent wrote, "The minivan’s size and functionality provide our team with significant flexibility to experiment with the self-driving rideshare experience. Much like our current fleet, these are hybrid vehicles — an important feature for us."

Aurora also plans to offer autonomous rides in its own modified Chrysler Pacificas.

Ford Fusion

The Ford Fusion and Lincoln MKZ are effectively the same base platform from a shared parent company, so the cars are similar and offer the same benefits for hardware teams. Uber started its self-driving testing with Ford Fusion Hybrids back in 2016. Ford's self-driving company, Argo AI, naturally opts for its own Fusion Hybrids in Miami, Washington, D.C., and other testing locations.

Chinese AV company DeepRoute AI also uses modified Ford Fusions, as seen above.

Over the years, the en vogue autonomous car has changed. Before 2016, Waymo used the Lexus RX450h and Toyota Prius. Apple's secretive Project Titan modifies a fleet of Lexus RX 450hs for public road testing.

But for now, I'm crowning the Chrysler Pacifica as the it autonomous car.