The question is a trope of the modern age. We were promised flying cars half a century ago; where are they?
The truth is, they're all doomed to fail. Flying cars are the modern equivalent of a faster horse. They're not what we really want. It's not the right question.
Go deeper. Ask why we want flying cars. To get there faster? Avoid traffic? Have a greater sense of freedom? Feel like we're living in the future?
If we find those questions and solve for them, we're likely to arrive at more interesting solutions. Less commuting; more geographic diversity; new kinds of mass transit; ideas we haven't conceived of yet.
It's a far more interesting, and more fruitful, way to look at the world. The science fiction of the past can give us hints about how we might solve these deeper needs, but they don't absolve us of having to discover them.