Is it technically classed as murder if you run some one over?

If you meant to, yes if he walked out in front of you or any other accidental issues, I should think no.

Added: (in the US) - If you hit the person on purpose it would be "murder." However - whether it happened on purpose or by accident the original charge brought against you would probably be "Homicide" or maybe "Vehicular Homicide." Upon investigation by law enforcement and the presentation of the facts to the prosecutor - if it WAS determined to be an 'accident" the charge against you would probably be reduced to "Manslaughter' (i.e.: causing accidental death without premeditation).