MiSpeedo

Response from developer

thanks for the feedback. The app displays the speed as reported by the phone's GPS sensor, so it's as accurate as the GPS signal (which will vary depending on time of day, location, weather conditions etc.), and, of course, your actual phone device . The speed displayed by the vehicle is set by manufacturer calibrations - UK legal regulations state that vehicles cannot allow you to go faster than the speedometer is reading. To ensure this regulation is met the UK allows 1-6 mph to be added to a car's displayed speed on its speedometer. Also, care must be taken to ensure that the correct tyre size and inflation are used - both of which will affect displayed speed (which is based on engine speed and/or wheel rotational speed). We'll add a facility for calibration to the car speed.