Quote from Eclipsed :

It's nice you're going the scientific way with all the calculations and I'm not...

after doing more research for this car top speed with electric limiter is about 190km i also find acceleration data and top speed with car unlocked (no electric limiter) its no more then 226km / 140mph , i also tested the car in game top speed and your right it does go a lot more then what it should be i manage to get 260km on stock setup and oem gear ratios, so i will consider updating the car giving it little more drag it may not going to be perfect but there has to be a sweet spot that we all agree on.
also if there is app or insim server that allow acceleration display to show times of acceleration so i can do more testing to get it near to "irl" that will be very helpful.

Easiest way probably would be using simple autocross start point (add split and finish line so time is counted) somewhere in layout square,do an acceleration test run by starting right at green light and save replay - when slowing down replay and pausing at correct time points,you can check the time at specific speed.