Hype necessarily recedes as the blunt realities of actually developing autonomous vehicles sets in. For the companies developing robotaxis, that means a scaling back of ambition (like Waymo) or the pushing back of timelines (just about every major OEM). In the trucking sector, we've seen this as a splash of cold water poured over the idea of driverless road trains speeding along highways. But a company called Peloton thinks that running two big rigs close together can still work—and still boost fuel efficiency and safety—as long as you keep human drivers in the cab and in the loop.

Although Peloton's PlatoonPro tech involves some clever vehicle-to-vehicle (V2V) and vehicle-to-cloud (V2C) technology, it only counts as level 1 automation on the SAE scale. That's because the system only links together the accelerating and braking functions in the platoon; the human driver in each cab is still responsible for steering and remains in charge.

Conceptually, the idea is an evolution of the adaptive cruise control system already fitted to many cars—and even some class 8 trucks—already on the road. These systems use information from a forward-looking radar to match the speed to a vehicle ahead, maintaining a constant gap between the two as the one in front speeds up or slows down. Peloton's approach leverages this idea, but it adds the V2C element (using 4G).

"We combine radar and direct communication between the trucks, which means closer following distances between vehicles," explained Josh Switkes, founder and CEO of Peloton. "When you use a radar sensor, you’re reacting to the motion you sense from the lead vehicle. This is limiting because when you first get the info that the front truck is slowing, it’s already gone through brake lag, but you still have to do that in the rear vehicle. Even if the system reacts quickly it will be behind. Second, you have no knowledge of the braking ability of the vehicle in front and how it compares to yours; trucks can differ in stopping distance by up to 150 feet," he told me.

As a result, trucks that are fitted with existing adaptive cruise control systems—like the Freightliner Cascadia we rode in at CES this year —leave around 3.5 seconds of headway to the vehicle in front. (A car, which is lighter and needs less distance to slow, is about 1.1 seconds.) The addition of the connected element in Peloton's system means that the second truck in the (two-truck) platoon knows within about 30 milliseconds that the truck in front has applied the brakes. What's more, it also knows how much that truck has applied them, whether that's a light application to scrub off a few miles per hour, or heavy braking.

Switkes also pointed out that because different trucks will have different braking performance based on things like the weight they're hauling or the state of their tires, the truck with the better stopping ability will always be the second truck in the platoon.

The immediate benefit from the system is an increase in fuel efficiency for both the lead and following trucks. "For a single truck, a third of its wind resistance is from the rear of the trailer. When you put two trucks together close enough, you not only save about 10 percent in fuel efficiency in the following truck [as it has less drag to push through], you also save about 4.5 percent on the lead truck," he said. "And because margins are so thin, they get excited even with these percentages of fuel savings—the typical fleet has single digit profit margins."

Demonstrating an increase in safety is not quite as simple as demonstrating the improvements in fuel consumption, but the topic is addressed at length in the company's recent safety report.

"There are a lot of claims out there with safety comparisons where people aren’t comparing like for like, for example comparing a vehicle to the general population of vehicles on the road, not to the same class," Switkes told Ars. "We've said we want the truck to be truly safer when you start platooning compared to right before you start platooning. That means comparing the same truck, on the same highway miles, and so on. The reality is that the rate of collisions for safe fleets with active safety is already pretty low—safe fleets have lower collision rates per mile than average consumer vehicles."

Switkes said that Peloton's tech is already being evaluated in a few initial deployments, although he wasn't prepared to get more specific at this time. The technology is agnostic when it comes to the trucks it's fitted to, and it enables platooning between trucks of different makes or trucks from different trucking fleets. As for the cost? Switkes wouldn't comment much there either. "It's dramatically lower than cost for Level 4 [geofenced fully autonomous] systems. Fleets get excited about the rapid payback numbers," he said.