No Longer a Dream: Silicon Valley Takes On the Flying Car - The New York Times

Final paragraphs

"“How is this going to work? I don’t want to be a Debbie Downer, but we can’t even take our cellphones on airplanes today because of fears about battery fires,” said Missy Cummings, the director of the Humans and Autonomy Laboratory at Duke University, who is researching personal air transport for NASA.

And don’t forget that flying cars will not be able to pull to the side of the road in an emergency, said John Leonard, a mechanical engineer at the Massachusetts Institute of Technology’s Computer Science and Artificial Intelligence Laboratory.

“Silicon Valley is full of very smart people, but they don’t always get the laws of physics,” he said. “Gravity is a formidable adversary.”"

No Longer a Dream: Silicon Valley Takes On the Flying Car - The New York Times