how can i make a count-up timer gui?

i'm trying to make a physical laptimer for my car, that starts timing once the driveseat (car.DriveSeat) touches a part called "Start", then stops once that part is touched again, and then updates the text inside three textlabels to display the minutes, seconds and miliseconds (hopefully in real time) that the timer is counting (the route for these is: car.Body.Laptime.Gui.(Minutes, Seconds And MSeconds), i've tried doing a while true do loop with a wait(0.01) and then adding to a value, but the timing was inaccurate and too fast, i've also tried "for i", didn't work either

could anyone help me with getting this to work? any help is greatly appreciated!