GuyT

Does anyone know the calculation for the actual speed of the car as taken from the rev counter. I am trying to work out how accurate the speedo is in my S4. I guess it will be a mix of RPM * 6 gear drive ratio * circumference of tyre.<p>At the moment I get some pretty linear readings from the speedo: ie<p>70 = 2600rpm<br>80 = 3000rpm<br>90 = 3400rpm<br>100 = 3800rpm<p>This gives a theoretical max speed (ignoring the limiter)of 177mph.<p>Just wondering how accurate this was !!