Air tab mounting

[usedgeo]

I bought 40 air tabs to put on my car. I know that they did not do much for a Prius and hurt an Insight's mileage. I would not expect much. I am trying to decide on the best locations. I am thinking back of roof and back of trunk. Then some in front of the front wheel wells. Then maybe some under the front bumper and some under the rear bumper.

I have fooled around with vortex generators on an airplane wing and they always involved a drag penalty for me. The fellow that claimed such a huge improvement on his Dodge truck put them near the leading edges. That might correlate with tripping the boundary layer on a round object but it is not what is generally recommended.

Any thoughts on this. These cost about as much as three tanks of gas so I don't expect payback just some interesting times.