Since the future isn't what it used to be, the folks at io9 looked at fiction versus reality for new car technologies. Sadly, the reality for flying cars is the hovercraft and the reality for Dr. Who's Motorway is congested streets. They are pretty optimistic about the Batmobile, however, which is something to look forward to.
There are many potential interactions that will affect how valuable any new technologies are. GPS devices are already talking with each other and providing great data about traffic. This new information and other pricing schemes have the potential to greatly reduce congestion, and if cars become self-driving congestion may not be as onerous as it is now. Whatever happens, many technologies will make driving easier, faster and more pleasant. That is great for drivers but will make it even harder to promote alternatives to driving for personal transportation.