If brake fluid levels are low, what could be the outcome?

When brake fluid levels are low, the most significant and immediate outcome is reduced braking efficiency. Brake fluid is crucial for transferring force from the brake pedal to the braking mechanism, allowing the vehicle to stop effectively. Low levels of brake fluid can result in air entering the braking system, leading to a spongy brake feel and diminished braking power. This can increase stopping distances, making it potentially dangerous under certain driving conditions.

In contrast, the other options do not relate to the function of brake fluid. Increased engine power pertains to the vehicle's engine performance, not braking. Enhanced fuel efficiency is affected by factors such as driving habits and vehicle maintenance, rather than brake fluid levels. Decreased tire friction involves the tire's interaction with the road, which isn't influenced by the amount of brake fluid present. Thus, reduced braking efficiency is the clear and direct consequence of low brake fluid levels.