Cover For Your Car Rolled In Rear Spoiler

Can anyone design and develop a spring loaded nylon (or similar material) cover for a family car that is encased in a cassette spool that itself is housed in the rear spoiler or rear bumper.

When drawn out, the cover should go over the top of the vehicle and hook on to a catch in the front bumper.





Neat, clean, functional are keywords here for the project.

The material is bound to wear thin in time and it should be easy to interchange worn parts with new replacements.

The covers should be available in multiple colours.

The cassettes should be of different widths to accommodate use on family vehicles of all sizes.

Neat, clean and functional - a concept brought to fruition and your vehicle is protected against the weather when not in use with very little effort.

Concept Sample: Traction Mat to Free Electrical Energy

  
Reduce>  Reuse> Recycle > Rethink> Repair

Traction Mat to Free Electrical Energy-
Having been thinking about this on and off over the last two decades...

If the drivers of vehicles cruising down a slope chose a lane with a traction mat that transferred pressure on its surface to a sort of ratcheted recoil, which in turn on achieving its threshold, released stored energy to drive a dynamo, we could harness quite a bit of electrical energy for 'free'. Vehicles driving over the 'traction mat' lane could accumulate points redeemable at service stations state-wide (of course, this would need the associated legislation).

What do you think? Is this doable? What are the variations to this concept? One that comes to mind immediately would be 'Speed bump -> Electrical Energy'