Hertz Global Holdings said Wednesday its car sales unit was partnering with Amazon.com's automotive retail platform, Amazon Autos, to sell pre-owned vehicles, sending the car rental company's shares up 9% before the bell.

The collaboration builds on Amazon Autos' recent expansion into used vehicle sales, Hertz said.

Hertz and Amazon will start offering the service in Dallas, Houston, Los Angeles and Seattle, with plans to expand to Hertz Car Sales' 45 locations across the United States.