Engineers are testing small, cartoonish-looking cars that have no steering wheel, no accelerator and no brakes. The two-seat electric prototypes with a 25 mph top speed are driverless vehicles guided by software, cameras and sensors using radar and lasers. Google commissioned 100 of the models from a Detroit factory for road tests near its headquarters in Palo Alto, Calif. It hopes to persuade state officials to allow a wider pilot program there in coming years.

On the outside, the experimental versions looks a bit like the ultracompact Fiat 500 or Mercedes-Benz Smart car. Inside are seatbelts, start and stop buttons and a screen that shows the pre-programmed route – but none of the regular controls that drivers touch. Because the route is preset, impulsive changes can't be made without stopping and entering a new destination. The car knows exactly where it is within a few centimeters – though only on roads already mapped in Google's database. The company still is many miles away from solving the challenge of driving in rain, fog or snow that could impede the electronic sensors, which "see" about 600 feet in all directions on a clear day or night.

Google isn't the only company that envisions self-driving cars in our future. Ford is working on a car able to park itself in a curbside space. Mercedes showed a driverless prototype at a German auto show last fall, and two other European automakers – Volvo and Audi – also are doing research. In Japan, Nissan predicts it will sell no-driver cars by 2020.

Test passenger says: "It felt a lot like a theme park ride. . . . I didn't feel unsafe in the least. The car braked for jaywalkers, paused when it was coming around a curve and couldn't see whether the light in front of us was green or red, and skittered when it worried that a bus might be turning into our lane." – Liz Gennes at re/code blog

Google co-founder says: "There is nothing to say that once you demonstrate the safety, why can't you go 100 miles per hour." – Sergey Brin

Mercedes executive says: "We are convinced that this technology will make fewer mistakes than a human." -- Eberhard Kaus, head of the autonomous driving team