Phew Glad I’m not going to be buying that car off you! Sounds to me that you are trying to brake the poor thing. The 172 will bang if you give it to many beans in first, the trick is to allow the power to be put on the road ( requires driver skill) , if you brake traction your 0.60 time is never going to be 6.5s
Besides the 0. 60 times are calculated in perfect conditions on perfect surfaces with optimal weather conditions and by very skilled drivers that understand the car. It sounds like the way you drive your car it wont be able to do 0 . 60 for to much longer. And that will be a good thing as you will need to get another car and hopefully it wont be a Clio and we wont have to endure you nonsense.
If its not sounding happy its because it isn’t , treat it with a bit of respect.