speedometer or sensor
 

1999 ML320 speedometer will not go back to zero. Will sometimes reset after turning it off and restarting but will read high. Problem is worse if ambient temperature is higher. When not started for a day and everything is still cold it will read correct until you stop at light and it will be reading from 10 to 30 and you are not moving. It will be off that much untill it cools off. Problem started after wife had to take evasive action from driver on wrong side of road and she had to drive partially in the ditch with very tall gras and weeds. Could it be a sensor?