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


Some of them pop up at much lower speeds - I think the Porsche 911 and
Audi TT spoilers pop up at 40 mph.