After doing some research, I've found that driving with a loose radiator cap is not safe. The radiator cap plays a crucial role in maintaining the engine's temperature and a loose one can lead to overheating. It can also lead to coolant leakage, which is detrimental to the car's performance and the environment. Plus, the cap's pressure helps to increase the coolant's boiling point, so without it, your engine could boil over. So, it's best to ensure your radiator cap is secure before hitting the road.