The car speeds provided are for modern cars. I don't know why they did this since the baseline campaign is 1920s, but check the footnote on the table. A 1920s car should indeed be MOV 11 or so.
As far as the windy road vs. flying, I think this is just a case where the keeper needs to exercise judgment. You could give flying creatures a MOV boost in such a case, or simply rule that the chase should proceed despite the MOV disadvantage because the chaser will have a much easier time avoiding hazards and barriers.
