How David fitted a Halfords "Windblocker" to his 1990 1.6i MX-5 - the object was to achieve a cheap solution to the wind buffeting problem.
Pictures are all THUMBNAILS - click on them for larger versions - you'll have to use the BACK button to return
Halfords sell a "Foldable Rear Sunshade" for £9.99 - below you can see the packet, what's inside (you also get rubber suckers to attach to a normal rear window - throw these away), and what it folds out to:
Installation is a simple matter of wedging the bottom centre behind the central console and looping the elastic (normally to keep it in the "closed" position - see above) around the relevant headrest. Although it looks insubstantial, the wind pressure at speed forces in against the headrests and certainly mine's been stable at speeds of 90mph (private roads of course...)
Since the windblocker is flexible, it doesn't interfere with raising and lowering the hood.
Mike Hawthorn has suggested an alternative method of retaining the windblocker in position. He's bought a couple of strong mobile phone magnets and carved out a bit of the foam in the headrest (remember it's zippered so easy to get at) to accommodate them. Then the metal plates which usually attach to the phone are stuck to the windblocker - these attach themselves to the magnet meaning the elastic strap can be dispensed with. The only proviso would be the means of attachment since I've found the adhesive on these plates softens with time - so drilling some small holes and sewing them on might be advisable.
Donutz supplies a very similar screen for less money - here's the direct link.
And here's an alternative one obtained for £1 at the local "Everything's £1" shop - needless to say it hasn't been, and won't be, fitted:
WARNING :
Any work you do, or have done, to your car as a result of reliance of this information is entirely your responsibility. You should check technical advice with an independent source, and take local specialist advice from a qualified person who has actually seen your car if in any doubt. I can accept NO RESPONSIBILITY for any damage caused to your person, car or property as a result of following or not following any procedure or advice given in this article.