Dhananjay Motwani is thinking of an animal, and his 20 Questions opponent is, question by question, trying to figure out what it is.

“Is it larger than a microwave oven?”

“Yes.”

“Can it do tricks?”

“Maybe.”

“Is it a predator?”

“No.”

“Is it soft?”

“No.”

“Is it a vegetarian?”

“Yes.”

What’s impressive here isn’t that the questioner is a computer; that’s old hat. It’s that the machine and Motwani are chatting in his blue Hyundai Sonata, trundling along one of Silicon Valley’s many freeways. The traffic, as it tends to be in this part of the country, is bad. The game is a good way not just to pass the time, but to show off what the Echo Auto can do as we creep toward the Sunnyvale lab where Amazon taught it to understand the human voice in the acoustic crucible that is the car.

Amazon introduced the road-going, Alexa-equipped device in September of last year, and started shipping to some customers in January. Amazon is working with some automakers to build Alexa into new cars, but the $50 Auto works with tens of millions of older vehicles already on the road: All you need is a power source (either a USB port or cigarette lighter) and a way to tap into the car’s speakers (Bluetooth or an aux cable).

About the size and shape of a cassette, the Echo Auto sits on your dashboard and brings 70,000 Alexa skills into your car. Its eight built-in microphones let you make phone calls, set reminders, compile shopping lists, find nearby restaurants and coffee shops, and hear Jake Gyllenhaal narrate The Great Gatsby.

An Artificial Head Measurement System with “the acoustically relevant structures of the human anatomy” plays a key role in Amazon's development of the Echo Auto. Amazon

Adding the Auto to a growing collection of Echo products makes sense. “There’s no better place for voice than in the car,” says Miriam Daniel, Amazon’s head of Echo products. Your hands are supposed to be on the wheel, your eyes on the road. But when she and her team started developing the thing about 18 months ago, they discovered that there’s no worse place than the car for making voice recognition actually work. “We thought the kitchen was the most challenging acoustic environment,” Daniel says. But family chatter and humming refrigerators proved easy to overcome compared to wind, air conditioning, rain, the radio, and road noise. “The car was like a war zone.”

To safely cross the aural minefield, Daniel’s team started by adapting the Echo’s hardware, software, and user interface to the car. That meant adjusting the device so it can handle being turned on and off frequently, and boot up in a few seconds instead of the minute and a half it took when they first tried it. The team adjusted its responses to be shorter. They added geolocation, so the device can point users to the nearest caffeine injection site. They disabled incoming “Drop Ins,” where approved friends and such can automatically connect to one’s Echo device for a chat.