Final answer:
Exceeding the Gross Combination Weight Rating of a vehicle with a trailer compromises safety and may reduce fuel efficiency while increasing the risk of brake overheating, not improved stability. A bouncing trailer is likely nearly empty as less weight would result in more pronounced movement in the suspension.
Step-by-step explanation:
If the Gross Combination Weight (GCW) of a vehicle and trailer exceeds the Gross Combination Weight Rating (GCWR), it means that the vehicle is not operating within safe limits. Consequently, the vehicle may experience reduced fuel efficiency due to the increased weight. More critically, there is a risk of brake overheating and reduced stopping power, which can lead to unsafe driving conditions. Exceeding the GCWR does not lead to increased stability and control; rather, it can compromise both safety and performance.
When observing a trailer bouncing up and down slowly on the highway, it is more likely that the trailer is nearly empty rather than heavily loaded. A heavily loaded trailer would have less bounce due to the increased weight damping the oscillations, leading to less pronounced movement. Conversely, a near-empty trailer has less mass to counteract the springiness of the suspension system, resulting in more noticeable bouncing.