Amazon has begun making deliveries in Los Angeles with the electric vans designed and built by EV startup Rivian.

The retail giant has ordered 100,000 electric vans from Rivian and while series production of the vehicle won’t commence until next year, these test vehicles are being used to fine-tune the finished product. Amazon hasn’t said precisely how many prototypes of the Rivian-built van it is currently using, but has confirmed the first road tests commenced four months ago.

Throughout 2021, Amazon will introduce its new all-electric delivery vans to an additional 15 cities. It has also started to alter its buildings to accommodate the new vehicle and has also installed thousands of charging stations at its delivery sites through North America and Europe.

Watch Also: Listen To The Annoying Sound Of Amazon’s Electric Rivian Delivery Vans

“We’re loving the enthusiasm from customers so far–from the photos we see online to the car fans who stop our drivers for a first-hand look at the vehicle,” director of Amazon’s global Fleet and products, Ross Rachey, said. “From what we’ve seen, this is one of the fastest modern commercial electrification programs, and we’re incredibly proud of that.”

Rivian’s delivery van is much more advanced than the more traditional ones used by Amazon. It features advanced highway driving and traffic assist features, a larger interior floor space in the cabin, exterior cameras offering a 360-degree view, three-level shelving, and advanced LED brake lights.

Amazon is also one of the most significant investors in Rivian, having led a $700 million funding round in February 2019 and also contributing to a recent $2.65 billion funding round through the Amazon Climate Pledge Fund.