A car mechanic was employed by his master, the defendant to repair cars. He repaired a car and then…

Liable because it was his servant who had negligently caused the accident for which he was vicariously liable

Not liable because the mechanic was supposed to repair only and as such driving by him was outside his course of employment

Liable because driving was necessarily incidental to the duties of the mechanic since he was duty-bound to check by driving whether the repair he had done were correctly done or not

It depends solely on the discretion of the court in such cases to decide as to whether the master is liable or not