What does a “collapsed” engine mount typically cause in a vehicle?

A "collapsed" engine mount refers to a situation where the mount, which is designed to secure the engine to the vehicle's frame, has failed or has been compressed beyond its intended capacity. This failure can lead to direct contact between the engine and the vehicle's chassis or surrounding components, which can result in excessive movement of the engine during operation.

When an engine mount collapses, it often allows the engine to vibrate more than normal because it is no longer properly secured in place. These vibrations can be felt throughout the vehicle, particularly in the cabin, and may lead to an uncomfortable driving experience. This mishap can also cause additional wear on other components if the engine bounces excessively, potentially leading to further mechanical issues.

While it could have secondary effects on fuel consumption, rough idling, or power output—such as an inefficient engine running due to misalignment or excess vibrations—the primary and most noticeable effect of a collapsed mount is the presence of vibrations. Hence, this makes the correct option relate to the vibrations caused by the engine being inadequately secured.