Final answer:
Motor/mobile fuel containers should not be mounted directly on a vehicle's roof, ahead of the front axle, or beyond the rear bumper due to safety concerns.
Step-by-step explanation:
It is not permissible for a motor/mobile fuel container to be mounted directly on a roof, ahead of the front axle, or beyond the rear bumper of a vehicle. This is because it poses safety risks, such as instability, increased chances of leaks or spills, and potential damage to the vehicle or the container itself during operation or in the event of an accident. Regulations and industry standards dictate the safe placement and secure mounting of fuel containers within vehicles, typically within the chassis or specialized compartments.