Astra 1.9cdti XP
Just bought Jeremy Clarksons No Limits and it pretty good.
There was the bit with the 172 (in red, looked very very nice) they had Jonathan Palmer driving round a track with 3 different sets of tyres. The standard one, some remoulds and some performance tyres.
The performance tyres were a second quicker than the standard and the remoulds were slower. I think the peformance tyres were Yokohama AVS Sport.
Just goes to show what difference a tyre can make!