Inflatable boat tail?
 

So I was thinking that the worst part of a boat tail is that it's mainly a highway thing... And that it becomes impractical around town (compared to the average hatchback anyway).

So why not have an inflatable boat tail? There's enough aero pressure differential available at highway speeds that you wouldn't need to have a powered inflation device under most conditions, but not so much that an easily available fan (say the centrifugal cabin fan found in most cars) wouldn't be able to overcome it for retraction at speed, should that be necessary. It would also be possible to rig the same fan for pressurisation at lower speeds should you brake suddenly (to avoid collapse, and to provide a super-large ever-present airbag for tailgating motorcyclists)

I'm not entirely sure how you would keep it rigid under strong crosswinds, but I think that the idea has merit.

Collapsed it would look much like those tow-bar cargo pods was covered in a loose tarp.

Thoughts?

http://ecomodder.com/forum/showthrea...ttail-896.html
Exhaust pressure has been suggested to fill as well.

In practice access to the trunk or hatch would need to be considered. A mount for the license plate is needed. Talk to your friendly upholstery shop that make boat covers.

http://ecomodder.com/forum/member-fr...pe-ii-boat.jpg

I didn't go back through the other thread, but this is probably in there. It models a hinged diverter with (because of the vehicle proportions) a stinger upright at the end. The rigid floor resolves a lot of the iffyness. At the time I showed air scoops along the front edge for inflation. I'd consider tube and skin or double-walled inflatable, else fiberglass rods that store along the roof driprail.