The actor/director, who is at the centre of a bitter custody battle with his ex-girlfriend Oksana Grigorieva, had to call a tow truck to Malibu Canyon Road to recover his battered Maserati after the crash.
Gibson was not hurt and a friend picked him up, according to TMZ.com.
According to the California Highway Patrol report of the accident, Gibson ""stopped his car at the scene and was contacted by officers from the West Valley CHP Area"".
CHP Public Information Officer Leland Tang tells TMZ.com, ""Gibson told officers in the field he did not know how the car drifted out of the lane and into the hillside.""
Alcohol was not a factor and Gibson insisted he was not speaking on a cellphone at the time of the crash.
Tang said police officers asked Gibson if he had fallen asleep at the wheel, adding, ""He did not give a firm yes or no.""