The company has nearly doubled its test fleet in the past two months.
Apple has apparently begun to accelerate deployment of autonomous test vehicles in California this year.
A year ago, the company had applied for permits to test just three autonomous cars in the state. The permits jumped to 27 by January 2018 and nearly doubled to 45 since then, according to DMV information obtained by Financial Times.
The findings were reported in relation to the recent pedestrian death involving an autonomous Volvo XC90 operated by Uber, one of nearly 400 such vehicles currently permitted to drive on public roads in the state.
Google's Waymo appears to have throttled back its presence in California, dropping from 100 permits last June to just two dozen today as the company prepares to launch the first commercial service in the Phoenix suburbs.
Apple's increase in vehicles now puts the company near the top in terms of California fleet size, second only to General Motors' Cruise division.