On Wednesday Ford announced that it would be testing a set of next-generation autonomous vehicles in 2017—a step along a path to building a market-ready, fully autonomous fleet for ride-hailing services by 2021. The automaker will triple the size of its test fleet in 2017, bringing the number of Ford research cars on US roads to 90.

Ford, like many traditional automakers, has been playing catch-up in the autonomous vehicle race after Google’s pioneering of the space and Tesla’s aggressive roll-out of its Advanced Driver Assist software. Where companies like Volvo are helping their customers stick their toes in the self-driving waters with systems that can take over driving on highways , Ford has decided it’s going to skip partial autonomy and go straight to the Society of Automotive Engineers’ (SAE) Level Four autonomy (PDF), or “High Automation,” where a driver does not need to intervene. Ford doesn’t intend to sell these cars to retail customers right away; instead it hopes to find customers in ride-hailing companies.

Ford says its next-generation autonomous test cars, all modified Ford Fusion Hybrids, will have two powerful lidar (light detection and ranging) sensors that “see” up to two football fields in any direction (this is down from four or five weaker lidar sensors in previous versions of Ford's prototype cars). The Fusion Hybrids will also have three cameras on the roof of the car, a camera mounted under the windshield, and short- and long-range radar sensors to detect objects in inclement weather.

Ford says this next generation of test cars has improved software, along with computing power that will “generate 1 terabyte of data an hour.” The extra computing power also requires the cars to draw extra power from both their gas engines and their high-voltage battery packs, with the help of two independent power converters.

Currently the Fusion Hybrids are capable of some pretty extraordinary things—like interpreting hand signals from police officers directing traffic—but they still have a long way to come to be fully autonomous. Ford specifically mentioned that it’s working on helping the car respond to ride-hailing-specific tasks, like figuring out what to do if a passenger has left items in the car or shutting a door that a passenger failed to shut. And it’s got to redesign the vehicle before it’s market-ready, because the finished product won’t have a steering wheel or pedals.

But those advancements will come at a later date, as Ford’s fleet logs more and more miles on public roads in Michigan, California, and Arizona in 2017.