Okay - I can answer this one fairly accurately!
I was at a track day at Donnington on 7th November in my Mk1 172 (Titanium - complete with easy-dent lightweight bonnet - shave those extra kilos!
) and I went round the track more than a few times with Telford_Mike and Matt - Leics, both in their Mk2 172s... Telford_Mike has a filter and cat-back Magnex (along with lowered suspension), Matt - Leics has a standard car and removed everything (just about!) from the inside of it to make it as light as possible. I have a SuperChip (rolling roaded +7bhp at wheels / +11bhp at flywheel) and left the car otherwise standard (complete with dirty air filter and shag*ed brakes!). Anyhow, to answer your question there was virtually nothing in it between all three cars... On the main straight leading up to the esses, I felt that I was able to gain a little (maybe one or two car lengths at most), but were talking of a flat-out race upto nearly 115/120mph!. It was by no means a crushing defeat to the Mk2 172s!!! I think that the cars (with their respective mods) all came out at a similar power-weight so thats why we were all about the same performance. Yes, the Mk1 172 is a bit lighter - but it also has slightly longer gearing (68mph in 2nd), thus stunting its performance a little. I dont know whether the longer gearing of the Mk1 may actually help or hinder it in a 0-60 sprint - maybe someone else can help clear that up...
Interestingly, the instructor who went out for a few laps with Telford_Mike, and then got in my car to take my dad out for a few laps (I know, I know - risky!!!
) apparently said to my dad that it pulled better than the other one (My dad has no real interest in Clios so I dont see why hed make it up). I think this simply goes to show that the Mk1 just feels more raw - it sounds harder and the throttle response is very punchy so it gives the impression of actually going harder... But without a few miles of runway, there was no chance of me going past either of em!
Whichever car has the better driver will win - Im certain of it... I know my car is firing on all cylinders and kicking out a full complement of horses (and then some!) so Im certain that the Mk2 172s I was playing with at Donnington were running every bit as fast as mine before the SuperChip. I still had em on the twisties though...
Sorry about the long post, but its the first topic in ages I actually have some real-life experience of... Woohoo! (All in my humble opinion of course)
Matt