"We are excited to have Amazon with us on our journey to create products, technology and experiences that reset expectations of what is possible," Rivian's CEO RJ Scaringe said.

Rivian revealed its R1T truck and R1S SUV in November, and shipments are expected to start next year. It's not entirely certain what Amazon's end game is with the investment. That said, it's clearly taking a deeper interest in transportation (which makes sense for a company that has delivery robots) as it also invested in a self-driving car company this month.