When driving in the middle of a downpour or during the night, most drivers flip on their headlights without ever giving them a second thought.

But a disturbing new study may force drivers to think differently and actually pay attention to their headlights.

The Insurance Institute of Highway Safety (IIHS) recently tested headlights on several midsize cars and the results that came back left a lot to be desired.

"If you're having trouble seeing behind the wheel at night, it could very well be your headlights and not your eyes that are to blame," David Zuby, IIHS executive vice president and chief research officer, said as part of the agency's research. "Our evaluation involves looking at both the high beams and the low beams, different paths along the test track."

How dismal were the results? Well, out of the 31 midsize cars tested, only the Toyota Prius v earned a solid rating ... but that's after the vehicle was upgraded to include LED lights and a high-beam assist — a package that Zuby says adds $7,000 to the cost of the automaker's model.

"The Prius v's LED low beams should give a driver traveling straight at 70 miles per hour enough time to identify an obstacle on the right side of the road, where the light is best, and brake to a stop," Matthew Brumbelow, an IIHS senior research engineer, said. "In contrast, someone with the halogen lights would need to drive 20 mph slower in order to avoid a crash."

Adding layers to its findings was the fact that the IIHS discovered just because cars are more expensive doesn't mean that they tout better quality lights. In fact, many of the poorest-rated headlights were installed on luxury vehicles such as the BMW 3 Series' halogen headlights.

Even cars outfitted with adaptive lights, such as the Kia Optima and Mercedes-Benz C-class, were rated poorly.

These findings are significant enough to possibly trigger an overhaul of cars' lighting systems by the auto industry. After all, headlights are a safety feature, especially during night driving.

"Over half of the fatal crashes that occur every year occur at night or at dusk or at dawn," Zuby said. "Helping drivers see the road better at night can help cut into those deaths and injuries."