To drive on **motorways**, vehicles must meet certain speed requirements. According to the regulations, **vehicles that are not capable of reaching a speed of 60 km/h on flat terrain** are **not allowed to drive**. This is because motorways are designed for the fast and safe transit of vehicles that can maintain higher speeds.

Additionally, there is a list of vehicles that are prohibited from accessing motorways and dual carriageways, such as **pedestrians, animals, bicycles, mopeds, and personal mobility vehicles**. These vehicles, by their nature, cannot reach the minimum required speed and, therefore, are not suitable for driving on these fast roads.


Therefore, the correct answer is that **vehicles that are not capable of reaching 60 km/h on flat terrain** cannot drive on motorways.