Someone backs into your $120,000 Porsche, you cuss and drive it with the ding until you get back home. Someone backs into your $120,000 flying car, you're stuck where you're at until you can get an A&P to fix it. Airplanes are MUCH more delicate in comparison to cars. ANY damage, and you're grounded. Doesn't have to happen overnight, either...could happen in the Cracker Barrel parking lot.
You've never traveled to another town to visit family or friends for a few days? Where do you park your car during the visit?
Insurance rates are not driven by the safe pilots, they're driven by the UNsafe ones. My guess is that the insurance for a flying car will run at least the same as for an amphibian...annual premiums can run to 10% of the aircraft's value. It'd be cheaper to buy and abandon a used car at every destination...
The issue is not whether a flying car is technologically feasible; Molt Taylor proved that fifty years ago. Economic viability is the issue. You end up spending a LOT of money to avoid having to transfer your bags to a rental car when you arrive at your destination. Remember, Molt had a TON of free advertising, with the main character of a popular TV show driving an Aerocar. Didn't translate into sales.
It's always possible to define a corner condition where a flying car is a viable option (Going to a small town that doesn't have any cab service or rental car companies!) but there aren't that many people who face that kind of situation...and without a market, the flying car cannot be economically viable.
I'm a bit more optimistic about rotorcraft and powered-parachute style flying cars, as the airfoil sections can be much more easily protected. But you don't get that much of an "aviation advantage" with these types of aircraft since they don't go much faster than a car on the interstate. My little $15,000 econobox can haul me and three friends from Seattle to Portland in about two and one-half hours. For $100,000 more, I can shave a half-hour off that time (less the time required to convert the flying car to/from aviation mode) as long as I leave two friends behind. Not seeing the advantage, really.
Ron Wanttaja