Last month, we wrote about a wave of startups like Nuro, Starship, and Marble that are building autonomous delivery vehicles. It's a promising concept. Designers of these vehicles don't need to worry about passenger comfort or safety (since there are no passengers). And vehicles can be slow—about 25 mph (40 kph) for Nuro, even slower for Starship and Marble—without irritating anyone inside the vehicle, which greatly simplifies the technical challenges of building a fully autonomous vehicle.

In our survey of this emerging market, we didn't mention another fascinating startup with a different twist on the same basic concept.

"It's not a delivery vehicle, it's an autonomous store on wheels," said Ali Ahmed, the CEO of Robomart, in a Tuesday interview with Ars.

Nuro imagines a future where the customer orders a few produce items and those specific items are delivered in an autonomous vehicle. In contrast, Robomart's plan is to effectively send the entire produce aisle to the customer's driveway. Then the customer walks outside, selects the items she wants, and Robomart automatically charges the credit card she has on file.

Ahmed points to a couple of advantages to this model. For perishable items like produce, customers will appreciate the ability to pick out items for themselves. Also, he argues, ordering groceries on an app is tedious and time-consuming—it's actually more convenient to just have a bunch of produce show up at your front door so you can pick what you want. On top of that, Ahmed argues that this kind of mobile grocery store will be able to make more deliveries per hour because it won't need to return to the store as often as a delivery vehicle does.

Robomart is such an early-stage startup—it was only founded last year—that it's impossible to predict if the company will be successful. The company has just seven employees and has only raised seed money so far.

For now, the team is punting on one of the biggest technological hurdle: the development of autonomous vehicle software. Early Robomart vehicles will be remotely operated by human drivers. Eventually, the company plans to switch over to fully autonomous vehicle technology. Robomart is building all-electric vehicles with a top speed of 25mph (40km/h), so the engineering challenges are somewhat simpler than building a car that can cruise down a freeway at 70mph (110km/h).

Another big hurdle will be automatically figuring out what the customer took out of the vehicle—a problem similar to the one Amazon is trying to solve with its Amazon Go concept. Ahmed argues that this is an easier problem for Robomart to solve than for Amazon because Robomart's "store" is much smaller and it only serves one customer at a time. There's no need to track multiple customers as they move through the store or figure out exactly which customer took a particular item off the shelf.

"We've built the first Robomart; it's here in our office at Alameda," Ahmed told Ars. "We're currently working on a batch of vehicles, and we want to put them out into a commercial pilot."

Robomart isn't planning to run its own network of grocery stores. Instead, it will lease its vehicles to grocery stores, who will put their own branding on them and be responsible for stocking the shelves and handling interactions with customers.

We don't know if Robomart will ultimately succeed in overcoming these hurdles, but what we found fascinating about the company was the way it illustrates how the rise of autonomous vehicle technology creates space for experimentation with new business models. There's no way to know if customers will prefer this approach over the alternatives, but in the next few years a bunch of companies are going to try a bunch of different models. And the results are likely to surprise us.