the weight difference between the 2 equated to that of a passenger, the rest is negligible due to say, amount of petrol in each car and the weight added by that. The real key is in the power:weight ratio:
clio 172: 156bhp/ton
clio 172 cup: 171 bhp/ton
clio182: 165bhp/ton
clio 182 cup: 168bhp/ton
clio trophy: 168bhp/ton
the 3-5 bhp difference between 182 derivatives and the 172 cup is not enough to make a noticeable difference on the road, and as the performance figures suggest, nor from a standing start either! Its all down to driver really.
when making your decision bear in mind that to really get the best out of a clio 172 cup over a FF 182 you'd have to be driving at full chat on every journey or in 'maximum attack' mode, and even then the difference is minimal.
sorry for the rant, it just annoys me when people try and tell me that the cup is faster