On Sat, 31 Jul 2010 19:55:31 +0100, Recliner wrote
"Tim Woodall" wrote in message
e.uk

Obviously, this breaks down for high performance cars at very high
speeds. I doubt that any road-legal car generates signficant down
force at speeds much below about 100mph due to the dire effect it has
on fuel consumption.

What about the sports cars which have retractable rear spoilers that pop
up at, say, ~75mph?

In many cases they have an appreciable effect at speeds not often reached in
the UK.

In order to give them some 'pose value' they are recalibrated to rise at
speeds more likely to be achieved in the UK, otherwise the driver might not
feel they're getting value for money/the required pose effect.

Of course, there is an argument that says a properly designed car shouldn't
need 'add-on' wings/spoilers etc fixed or otherwise.