Tesla debuted its "fully self-driving" computers this past April and has already installed the hardware into newer Model S, X, and 3 vehicles.This year, Tesla may start retrofitting those chips into older cars.

According to a tweet from Tesla CEO Elon Musk, retrofitting will "most likely" begin toward the end of this year. Only Tesla vehicles with Autopilot Hardware 2 are eligible for the new computer. Customers also needed to order the "full self-drive" option when configuring their new Tesla. The option cost an extra $6,000, though the Tesla chief said there are some 500,000 vehicles eligible for the upgrade. Not all of them will get it, obviously.

The new computer, per Musk, will give Tesla cars the ability to drive themselves by the end of 2020. Rather than fit cars with lidar and other equipment most companies working on autonomous driving technology use, Musk and Tesla plan for a "neural network."

2019 Tesla Model X

2019 Tesla Model X

In the April announcement, the CEO said the computer and the car's camera and sensors would provide all the data needed to teach other cars how to drive themselves. The neural network uses human annotators to identify common sights on the road, such as other cars, pedestrians, and cyclists. All of the data is fed to the in-house-designed Tesla computer. Two of the fully self-driving computer chips are onboard for safety redundancy purposes. All the while, Musk has touted the chips are cheaper to produce than the Nvidia chips they replace and they're 21 times more powerful. (Nvidia disputed the latter claim, however.)

Tesla and Musk have been a little loose with timelines, so it's unclear if the automaker can make good on the timeline, but it's a place to start.