The victim had left his vehicle in Clare Road to deliver a parcel at around 5.30pm last night.
It was then that another man entered the vehicle and attempted to drive off.
In doing so, he collided with the victim causing serious injuries.
The suspect then drove off, colliding with two cars, before decamping and leaving the vehicle on Frobisher Crescent.
Members of the public managed to detain the suspect until officers arrived at the scene.
A 45-year-old man was arrested.