While the company has yet to confirm anything, information about the project has been leaking out sporadically over the past several years.
On May 14, the California Department of Motor Vehicles (DMV) confirmed (via macReports) that Apple now has 55 vehicles and 83 drivers permitted to test autonomous vehicles.
One important thing to note here is that Apple has yet to apply for a separate driverless testing permit, which would allow the company to test autonomous vehicles without a person in the car. The California DMV began issuing driverless permits in April of this year.
To put this into perspective, Apple had roughly 45 self-driving vehicles back in January of this year. Apple’s self-driving efforts have been somewhat confusing over the past year or so, with most rumors suggesting that Apple will build its autonomous software/hardware suite, but will license it to other manufacturers to use it rather than building its own Apple-branded car.