Wouldn’t it be nice to own a self-driving car? You could skip all of the traffic, read the newspaper and drink a latte on the way to work every morning.

Although, self-driving cars might be the next big thing in Silicon Valley, you won’t seem them on roads for another decade or so, says Marketplace Tech host Ben Johnson. There’s still a lot of work to make them street-ready, and right now they come with a hefty price tag: about $320,000.

“Your average American family can apparently afford to spend maybe about twenty grand on a car, so cost is a problem,” Johnson says.

Google’s self-driving cars have some GPS problems, but programming the software to respond to changing, unpredictable driving conditions is another issue.

“Software is really good at dealing with stuff that it’s been designed to deal with,” Johnson says. “It’s way harder for you to design software to deal with data that it has not predicted yet.”