Hi Jody -
See the attached pic.
I made this one, actually. It's just a rectangle of outdoor appropriate black vinyl with:
- a cord attatched at each corner with hooks on the ends to pull it taut horizontally towards the wheel arches
- five "tabs" (2 top, 3 bottom) to stretch it taut vertically (you can see the 2 top tabs just inboard of the turn signals - they hook on the top aft edge of the bumper cover)
- a hole for the block heater cord
- one permanent cooling opening, about 6 in. by 4 in, with a mesh screen (which you can't really see in the pic)
- there's a second cooling opening (outboard of the permanent one) that has a velcro secured trap door/flap. I put it there just in case, but I've never had to open it.
This took me about 1 to 2 hours to make, and materials cost maybe 15 bucks from a fabric shop.
If you can find a commercial bra designed to fit your car, that would be the easiest route. But you would obviously have to modify it (it would still have too many openings).