First it was in-home deliveries, now Amazon wants to deliver goods directly to the trunk of your car.

The ecommerce giant today announced a partnership with General Motors that will open up in-trunk deliveries to 2015 (and newer) connected Chevrolet, Buick, GMC, and Cadillac vehicles with an active OnStar remote access subscription, in addition to Volvo vehicles with an On Call account.

Back in October, Amazon announced its new Amazon Key in-home delivery service, which is powered by a camera and smart lock, and the company then went all-in on the smart home by acquiring smart doorbell maker Ring for more than $1 billion. The Amazon Key In-Car service represents an expansion of that initiative, enabling Prime subscribers with one of the aforementioned compatible vehicles to have a package delivered directly to their car while it’s parked in an easy-to-access location.

The service is open to 37 cities across the U.S. from today, though the company had given early access to a number of people in the buildup to this launch, and made this video here.

While deliveries are generally limited to goods that can fit inside a car trunk — such as groceries, some electronics, and daily essentials — Amazon said larger packages may also be left in the vehicle’s main cabin space. That is an interesting admission, given that parcels visible to passers-by on the street may be more attractive to window-smashing thieves.

How it works

Drivers must connect their Amazon Prime account to the associated online account for their vehicle, which is done through the Amazon Key mobile app. If you live in an area eligible for in-car delivery, you’ll see this as an option in the Amazon shopping app or website.

On the day and time allocated for your in-car delivery, which is provided on the day with a four-hour window, you need to ensure that your vehicle is parked “within two blocks” of the default delivery address associated with your Amazon account. If you end up moving your car for whatever reason, the delivery is made to a physical address or rescheduled for in-car delivery the following day — depending on what you have pre-selected as your backup. Customers can also track the delivery status of the package through their device and receive real-time alerts.

As with in-home deliveries, the delivery person isn’t given any access code or key to open your car — it’s all done through an “encrypted authentication process” that verifies the driver is present at the correct location of the car with the correct package in their hand, data that is used to then unlock the car. The car owner then receives an alert confirming that the delivery has been made.

Above: Item Delivered

“Receiving a package securely and reliably in your car, without you having to be there, is something we think many people will appreciate,” said Volvo’s chief digital officer, Atif Rafiq. “Our partnership with Amazon now makes this possible for a majority of our customers in the U.S. This intersection between transportation and commerce could very well be the next wave of innovation, and we intend to be at the forefront.”

This isn’t the first time Amazon has ventured into in-car deliveries — the company ran a small test in Germany with Audi way back in 2015, though this required access codes, and the project was ultimately not extended beyond the trial. News then emerged last October that Amazon was once again exploring in-car deliveries.

“Since launching Amazon Key last November, we’ve safely delivered everything from cameras to collectible coins inside the home,” added Peter Larsen, vice president of delivery technology at Amazon. “Customers have also told us they love features like keyless guest access and being able to monitor their front door from anywhere with the Amazon Key App. In-car delivery gives customers that same peace of mind and allows them to take the Amazon experience with them.”

Amazon said it will add support for more connected car manufacturers over time.