What is a common result of excessive speed during a rainstorm?

Excessive speed during a rainstorm can lead to hydroplaning, which occurs when a vehicle's tires lose contact with the road due to a thin layer of water on the surface. At higher speeds, water can build up between the tire and the road, causing the vehicle to glide uncontrollably over the water instead of maintaining traction. This significantly diminishes the driver's ability to steer and brake effectively, increasing the risk of losing control of the vehicle.

Considering the other options, while increased braking distance and decreased fuel efficiency can indeed occur during adverse weather conditions, they are not the most direct or critical consequence of driving too fast in the rain compared to hydroplaning. Improved visibility is generally not associated with rain, especially not when driving at high speeds. Hydroplaning stands out as the most hazardous and immediate result of speeding in wet conditions.