No person transported by an owner or operator of a motor vehicle as his guest without payment for such transportation shall have a cause of action for damages against such motor vehicle or its owner or operator for injury, death or loss in case of an accident unless such accident shall have been intentional on the part of such owner or operator or caused by his heedlessness or his reckless disregard of the rights of others.

This section shall not relieve a public carrier or any owner or operator of a motor vehicle which is being demonstrated to a prospective purchaser of responsibility for any injuries sustained by a passenger while being transported by such public carrier or while such motor vehicle is being so demonstrated.