(Reuters) - Amazon.com's ( AMZN ) self-driving car unit, Zoox, is seeking to stay abreast of rival Waymo by expanding its vehicles' testing in California and Nevada to include a wider area, higher speeds and nighttime driving.

The changes, announced on Thursday, apply to Zoox's fleet of vehicles that it designed and built itself. Those resemble toaster ovens on wheels and lack manual controls inside, like steering wheels, pedals and gear shifters. Zoox also operates retrofitted self-driving Toyota Highlanders in Seattle, Las Vegas, San Francisco and Foster City, California.

The moves are modest compared with Alphabet's Waymo, which this week announced a plan to begin a taxi service in Los Angeles, on top of the existing markets of San Francisco and Phoenix, where it already ferries passengers in its retrofitted autonomous Jaguars.

Zoox said it will free up its specially designed vehicles to drive at speeds up to 45 miles per hour (72 kph), from 35 mph. It also expanded the Las Vegas area in which the cars can travel to five miles from one mile, it said in a statement. "Driving in these larger areas exposes our robotaxis to the busiest conditions they've ever encountered," the company said.

The Zoox vehicles will also drive in light rain and at night, the company said, critical for gathering additional data.

Like rivals, Zoox is hoping to one day replace human drivers with full self-driving vehicles that technologists say are safer and more reliable because they do not succumb to human error. Zoox has not given a timeline for when it thinks its fully autonomous vehicles will be ubiquitous.

Rival General Motors' Cruise halted testing of its robotaxis last year after regulators alleged executives had withheld evidence from an accident in San Francisco in which a Cruise vehicle struck and dragged a woman about 20 feet (6.1 m)after she was hit by a human-driven car.

Amazon ( AMZN ) bought Zoox in 2020 for more than $1 billion, leading to speculation it could eventually use the cars as delivery vehicles, sparing it the cost of paying for drivers. Zoox has not made any announcements about its plans beyond as robotaxis.