Surface Face flip

Im not sure how to do this with a Surface. But with a mesh you can make an object two sided or flip the face to the opposite side. Well, im creating a car and when duplicating a Surface and fliping it along one of the axis, the face is now towards the inside of the car. Any ways to fix this without havign to covert to mesh?

Thanks,
Danny

select one CV and select Change Direction in the Wkey menu.

Martin