New technology makes some cars smarter than their drivers: Automatic braking systems slow or stop cars to prevent collisions. Lane-departure warning features alert drivers with sounds or vibrations when their cars drift across lane markings.

But the cost of crashes and auto insurance have risen sharply in recent years.

What gives? For one, a lot of older cars are still on the road. Even if the new safety features ultimately reduce crashes, it will take time for them to make a dent in the accident rate. The average age of cars on U.S. roads is more than 11 years, said researchers at IHS Markit.

For another, we are driving more than ever, thanks to a better economy and job market, according to Arbella Insurance Group.

Drivers logged more than 3.2 trillion miles on U.S. roads in 2016, the fifth straight year that U.S. mileage increased, according to the Federal Highway Administration.

More miles means more crashes. And more crashes lead to more drivers filing insurance claims, said the Insurance Information Institute, a trade group.

The number of collision insurance claims per insured vehicles has crept up every year since 2013.

Both medical and car-repair costs are rising. Insurers' costs to pay and administer claims went up 11 percent or more per insured vehicle in the past two years, depending on the kind of claim, the Insurance Information Institute said.

Technology is partly to blame for the higher costs. According to Arbella claims information, windshields on cars with advanced driver-assistance systems, such as adaptive cruise control, can cost 82 percent more to replace than vehicles without those features.

In addition, changes in vehicle composition, including the increased use of aluminum, boost labor costs for repairs.

Most car insurers don't yet offer discounts for the latest features, such as adaptive cruise control, automatic emergency braking or lane-departure warning systems. (Liberty Mutual is an exception.)

"These features are still new and so far very few vehicles on the road are equipped with them," said Russ Rader, a spokesman for the Insurance Institute for Highway Safety, a research and educational group supported by insurers.

"Insurers need historical data on whether these systems are reducing claim costs for specific models," he said.

Another challenge for insurers is confirming whether a vehicle has those features. Usually, they get a snapshot of a car by checking its vehicle identification number, or VIN, a unique 17-digit code created by the automaker. The VIN identifies the car's specifications and manufacturer but doesn't include whether a vehicle has advanced crash-avoidance features like automatic braking.

"Once automakers make a feature like autobrake standard equipment rather than optional, it will be easier for insurers to track," Rader said.

Although advanced safety features might not yield a discount yet with many insurers, Rader said they are worth considering when buying a car.

"Consumers should look at these features as important safety equipment," he said. "If you buy a vehicle with crash avoidance technology, and it prevents just one crash, the system probably paid for itself."

Barbara Marquand writes for NerdWallet, a personal finance website.