Amazon's autonomous vehicle subsidiary Zoox announced it will begin testing its self-driving cars in Dallas and Phoenix, expanding to 10 US cities total. The company will initially deploy retrofitted Toyota Highlander SUVs with human safety drivers to map the new cities before eventually rolling out its purpose-built robotaxis.

Zoox says the two new markets offer unique testing conditions its vehicles haven't encountered before. Phoenix presents extreme heat, dust and high-speed roads, while Dallas features sprawling roads and varied weather patterns. The company is also opening new depots in both cities and a command hub in Scottsdale, Arizona to handle fleet operations and rider support.

Amazon acquired Zoox for $1.3 billion in 2020, and the company reports its fleet has driven over one million autonomous miles and served more than 300,000 riders to date. The expansion comes as competition in the robotaxi market intensifies, with Alphabet-owned Waymo rapidly expanding across the US while Tesla's Robotaxis remain limited to parts of Austin, Texas. US regulators are set to hold a self-driving safety forum this week with CEOs from Waymo, Zoox and Aurora expected to attend.