Kill switch engage

Climbing into the car, the first thing that strikes you is how ordinary it looks. The interior of the RX450h has the same leather seats and wood accents as a normal Lexus hybrid, and there are few signs that show it has been transformed. The most prominent change is a giant red button that has been installed just below the gear shift. This is the master kill switch, and pressing it disables the autonomous capabilities instantly. "If you hit this down, you have a Lexus," says Nick Van Derpool, who has climbed into the passenger seat and will spend our trip recording feedback to pass on to the company's engineers. The goal for our roughly 25-minute cruise around Mountain View: avoid having to hit the kill switch.

Our vehicle also has modified steering, with separate "on" and "off" buttons for the autonomous driving software placed on either side of the wheel. Our "driver," Ryan Espinosa, also has a heads-up display mounted above the wheel that shows him a 360-degree view of what the car is seeing, and how fast it's driving. As he pulls out of the museum driveway, a chiming noise echoes from the speakers, and a woman's voice lets us know that automatic driving mode is now on. The car begins driving itself through the streets of Mountain View.

"The ideal ride is meant to bore you," Epinosa says. And sure enough, as we begin making our way down Rengstorff Avenue, I'm struck by how impossibly ordinary our drive feels. Espinosa is sitting in the driver's seat, closely monitoring traffic, and the car is making turns and changing lanes with a smoothness and precision that I associate with my high-school driving instructor. From the backseat, the only tell that a computer is driving is the fact that the wheel is spinning independently of Espinosa's hands: it turns left and right independently, as if it were a ride at Disneyland.

Cruising down Rengstorff at a precise 35 mph, the light turns yellow ahead. We're far enough away that I probably would have stopped. But unlike the car, I don't have perfect awareness of my speed, the distance ahead, and how long the signal has been yellow since I noticed. The car I am in is drawing on a combined 700,000 miles traveled and 40 years of driving history built into its memory, and precise maps of Mountain View's 2,000-plus traffic signals. We sail through the intersection before it turns red.