Folding wings

OK, you have to humor me on this.
I'm not talking about anything unrealistic (like Moller's skycar, etc).
But what would prevent a design (even low performance/ultra light to start)
that would allow a pilot to fly into an airport, then fold up his wings and
cruise down surface streets at 45mph?

It doesn't sound that complex. I bet a homebuilder could do it with parts
laying around his garage.
The only serious issue I can think of is having a spinning prop on a city
street.
Even so, couldn't you "disengage" the prop and then couple the engine to the
mains somehow?
I realize that is a bit more complex and would mean some kind of
transmission.
I'm just throwing out ideas here.

It sure would be nice not to rent a car or get a taxi!
It also seems that there would be a MUCH larger interest in GA if people
could potentially commute this way.
For example, I would consider working in Reno and living in Minden if I
could fly into Reno, then commute to my work.

I'm serious about this, but I'm ready for the flames ;-)

Adam
N7966L
Beech Super III