hmmm, with regards to fast or slow 172s: Mine feels slow when its cold i.e. left outside all night and first driver out of my road. It kinda surges and does all sorts of weird things while its warming up. Once its been warmed up for about 15-20 mins then its pretty quick. Also its really quick after its been given a fast run, turned off and then turned on again. It kinda has a time out or a rest and then wants to play again. To be honest tho, once warm its pretty much consistantly quick. Remember, the clio engine bay is tres small so lots of heat builds up in there and probably gets sucked into the engine. Its had a couple of slow moments that are really noticeable, but my last car had these. Its just a factor of what happens to your car, probably linked to engine temp, quality of fuel - perhaps some crap got into the injectors? carbon or whatever. Maybe sucking in too many fumes from the car in front!!
My car felt slowest when i once was messing around taking off the cold air feed pipes to make it sound meaty. I connected them up and my car felt AWFULLY slow. I was thinking, "oh no, ive sucked some mailto:cr@p">cr@p in there and its screwed up", but what had really happened was that id disconnected the pipes to the airbox wrongly and they were squeezing each other too tightly! instead of 172 it felt more like 72!!! have a check of your pipes all you guys with "slow" 172s. Perhaps the factory of the garage connected them wrongly (easy to do) and theyre fouling each other. Just think of it like this. Is it easier to breath through a straw or through a normal mouth? you know the answer. Im always checking to see that the pipes are "round-shaped" and not squashed by squeezing them. Have a good look dudes.......