Starting today, residents of Scottsdale, Arizona have the opportunity to receive autonomous grocery deliveries from Fry's Food Stores—a brand owned by grocery giant Kroger. The technology is supplied by Nuro, a self-driving vehicle startup founded by two veterans of Google's self-driving car project. We profiled the company in May.

Kroger says that deliveries will have a flat $5.95 delivery fee, and customers can schedule same-day or next-day deliveries. Initially, the deliveries will be made by Nuro's fleet of modified Toyota Priuses with a safety driver behind the wheel. But Kroger expects to start using Nuro's production model—which doesn't even have space for a driver—this fall.

That vehicle, known as the R1, is significantly smaller and lighter than a conventional passenger car. When we talked to Nuro cofounder Dave Ferguson back in May, he argued that the R1's design had significant safety benefits. A smaller, lighter vehicle would do less damage if it ever ran into something. The vehicle's maximum speed of 25 miles per hour also makes serious injuries less likely.

And the fact that the car is dramatically narrower than a traditional car gives it significant safety benefits, Ferguson argued.

"We have an extra 3-4 foot of safety buffer in terms of width that we can dynamically position around the vehicle," Ferguson told us. For example, suppose there is a row of parked cars on one side of a Nuro vehicle; it can then hug the opposite side of its lane, giving it more time to brake if a child darts out between two parked cars.

Kroger runs grocery store chains across the country. Arizona has some of the nation's most permissive laws regarding driverless vehicles, which was likely a factor in Kroger's decision to launch its first delivery service there. But if the project is successful, we can expect the program to be extended to other areas.