A $1,000 hands-free driving device enabled an aging Prius to travel coast-to-coast with 99% autonomy.

      Courtesy of Jay Roberts

      The latest in car news and reviews, without the fluff.

      Our complimentary daily newsletter delivers the most significant stories straight to you every weekday.

      About 1,500 miles into their Cannonball Run attempt heading west, Jay and Gypsy Roberts encountered some challenges.

      “We were passing through Oklahoma when a tornado hit just under two miles from Interstate 40. It was genuinely intense, with strong winds,” Jay described during our phone call. “There was water on the road, visibility was poor, and it was nighttime, which made it even riskier. My wife Gypsy was at the wheel, and we decided to reduce our speed to about 50 or 55 miles per hour.”

      Severe weather can jeopardize any cross-country journey, but focus and cautious driving wouldn’t be enough for Jay and Gypsy to navigate this ordeal. Their 2017 Toyota Prius was fitted with a device known as a Comma 3X, which took over the driving duties for them. This $1,000 device connects to the OBD-II port of a car and is mounted on the windshield just below the rearview mirror, enhancing semi-autonomous capabilities. Comma claims it supports over 325 different vehicle models.

      In this instance, it was steering an eight-year-old Prius with a quarter-million miles on the odometer through heavy rain and wind.

      Jay mentioned that the Comma 3X handled the storm “perfectly,” unlike other built-in advanced driver-assist technologies—such as Tesla’s Full Self-Driving—which would have disengaged. This was crucial, as Jay and Gypsy had undertaken a semi-autonomous Cannonball Run: a variation of the coast-to-coast driving challenge that emphasizes minimizing human involvement while racing against time.

      Jay and Gypsy Roberts. Courtesy of Jay Roberts

      Establishing a New Kind of Record

      Jay is experienced with the Cannonball, having completed the journey both manually and with assistance five times prior to this latest semi-autonomous attempt in April of this year. In 2024, he and Gypsy finished the trip in 43 hours and 18 minutes, nearly 12 hours faster than record-seeker Alex Roy, who completed it with two partners about a decade ago in a Tesla Model S.

      Of the total 43 hours, the couple reported they only had their hands on the Prius’ steering wheel for 39 minutes and 21 seconds—indicating the Comma 3X controlled the Prius for 98.416% of the trip. In December, Roy completed a 45-hour and 36-minute drive in a 2025 Model S, with an even higher engagement rate of 98.52%.

      There are clear distinctions between how a plug-and-play system like Comma operates compared to built-in systems, and both Cannonball and autonomous-driving enthusiasts are welcome to analyze and categorize the data as they wish. For Jay, he realized there was potential for improvement. During the 2024 attempt, they encountered a significant accident in West Texas that caused a three-hour traffic jam. Furthermore, Jay had not modified the Prius' fuel storage for that journey, resulting in six fuel stops.

      “What we discovered was that every fuel stop or driver change added two to three minutes of hands-on time to the system,” Jay explained. For this year’s run, a 32-gallon auxiliary tank was installed alongside the stock 11.3-gallon capacity, allowing them to stop for gas only once, just east of Amarillo, Texas. This adjustment saved both time and steering-wheel contact.

      “Transitioning from six fuel stops to just one eliminated 10 to 15 minutes of hands-on time right there,” Jay noted.

      Top left: Jay is shown with his electrically conductive jacket and gloves. Top right: A close-up of the taped steering wheel. The Comma 3X is mounted on the windshield, in place of where you would typically find a GPS. Bottom: Readouts installed by Jay showing the number of touches and total time of contact at the end of the trip. Courtesy of Jay Roberts

      You might wonder how Jay tracked hands-on time; since Comma doesn’t log that data, he had to get inventive. His creative solution involved wrapping the steering wheel with conductive tape and wearing conductive jackets and gloves connected to a power supply when they were seated in the driver's position. The number of contact instances, along with the total time the circuit was completed, were recorded and displayed on two LCD readouts mounted on the dashboard.

      The protocol on the road was straightforward. The Comma 3X, utilizing its stock OpenPilot software, was set to cruise at 91 mph, with the Prius maintaining position in the left lane. If another car entered its lane, the Prius would slow to match its speed and follow until the other vehicle moved away. Jay and Gypsy avoided flashing their high beams at cars ahead and only changed lanes when absolutely necessary, as the system requires some level of human