We've already seen several companies outside of the auto industry invest in self-driving technology, such as Apple and Google's Alphabet. It's perhaps surprising, then, that it's taken this long for Amazon to jump on the autonomous car bandwagon.

The online retail giant has invested in Aurora Innovation, a self-driving start-up run by former Tesla and Google executives. In total, Aurora has secured $530 million thanks to investments from Amazon, Sequoia and "accounts advised by T. Rowe Price Associates," but it isn't known how much Amazon contributed towards the investment.

The company highlighted that Amazon's "unique expertise, capabilities and perspectives will be valuable for us as we drive towards our mission" and that this latest investment will help accelerate development of their autonomous driving technology and strengthen their team and ecosystem.

Aurora Innovation was founded by Chris Urmson, Sterling Anderson and Drew Bagnell, who have years of experience in the industry. Urmson was the Chief Technology Officer for autonomous vehicles at Google's Alphabet, while Anderson led the team that created Tesla's Autopilot. The experienced team also includes Drew Bagnell from Uber's self-driving development.

Last year, Aurora also partnered with Hyundai and Volkswagen to develop Level 4 autonomous vehicles that are expected to arrive by 2021. The partnership will initially focus on custom-developed vehicles, but the two companies will work to "commercialize self-driving vehicles worldwide" in the long term.

There hasn't been any news about the partnership since it was initially announced last January, but Level 4 vehicles can drive themselves without any human intervention in certain conditions. At the time, the two companies said the goal of the partnership was to deploy these vehicles "quickly, broadly and safely."

It will be interesting to see what Amazon's involvement will bring, but this isn't the first time the online retailer has collaborated with the auto industry. Amazon's Alexa voice assistant has been integrated into several cars, and the company also offers a service allowing customers to accept deliveries in the trunk of their car.