Speedometer. An automobile speedometer with an in- built mileometer (bottom centre). The speedometer pointer can be seen at bottom centre. The speedometer has two speed scales. The outside scale is in miles per hour (mph) and the inner scale is in kilometres per hour (km/h). The speedometer pointer can be operated by several mechanisms including direct mechanical means, magnetic fields and electric pulses. The mileometer is a display of the total distance travelled in miles by the vehicle.