Is there any particular reason you dont want the one that go on the inside of the window?
But, yes, there should be somthing that will answer your needs.
One idea is sinilar to what some car alarms use, in that the antena is a piece of wire that you run up the inside of the A piller trim. You may be able to stash a rubber duckie antenna, or even a full normal antenna in the A piller trim of your car.
Reception may suffer tho...
apart from that i have seen a small antenna that would suit, but it was custom built by a friend whos an RF engineer. Still, the old coat hanger can do wonders...