A Ford Focus left the Mountain Road and crashed through fencing near the 28th Milestone on Wednesday evening.
And police are investigating the possiblity it made contact with another vehicle during an overtaking manoeuvre.
An appeal has been issued for any witnesses to come forward to the incident, which took place at around 8pm.
A statement from the police says: ‘It is reported that whilst a vehicle travelling towards the Douglas direction has been in the process of making an overtake, another car travelling in the same direction has also pulled out and potentially made contact with the first car which has then crashed through the fencing and gone down the hillside.’
Constable Mark Kerruish said: ‘It is fortunate that no one was injured in this incident, and we appeal for anyone who may have witnessed the incident or who would have been travelling over the Mountain Road towards Douglas at that time in a grey or silver-coloured Citroen Picasso vehicle to contact Ramsey Police Station on 812234.’