Originated From Worldcarfans
Have you checked that there is sufficient coolant/water in the radiator? And that there is sufficient airflow through the radiator? If both of these are ok then the most likely explanation would be a blockage in the coolant system.
Sounds like a defect in the specific car you were driving. These defects happen sometimes though they are extremely rare. I don't think this is something the represents the 318i series.
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them