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Properly installing child seats into vehicles continues to be a challenge for parents and other caregivers, but new vehicle designs are improving the odds that you’ll be able to install a car seat securely, according to new data released by the Insurance Institute for Highway Safety.

The organization just presented its latest ratings. The 2016 Toyota Prius, 2016 Lexus RX, and 2017 Audi Q7 earned the organization’s Good+ rating, a distinction that no vehicles were able to achieve in 2015.

Studies have shown that many, if not most, child seats are installed improperly, putting children at grave risk in an accident. Motor vehicle crashes are a leading cause of death in children over the age of one, according to the Centers for Disease Control. Even 1 inch of side-to-side movement of a car seat in an accident can transfer forces capable of injury to a child.

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LATCH (Lower Anchors and Tethers for Children) positions in cars, trucks, and SUVs aim to make it easier to properly install a car seat. You no longer have to deal with weaving the spaghetti of seat belts through the child safety seats; instead, you use a system of clips and tethers to secure the seat.

LATCH car seat installations themselves are not necessarily safer than child seats properly installed using seat belts, but the odds of proper installation using LATCH are much greater. LATCH hardware has been required in all new cars since 2002, but the implementation of the anchor and tether systems by various carmakers has been inconsistent. Some of the seat anchors and tether locations are buried too deep in the seat, are not positioned well, are not clearly labeled, or are not easy to maneuver around, according to IIHS.

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IIHS launched its child seat anchor ratings program in 2015, rating 102 vehicles in its first year. Most were found to be poor or marginal in that initial round of testing. This year, the organization tested 170 vehicles, and most were rated good or acceptable. The full results of the testing can be found here and on each vehicle model’s crash test results page.

"Frustrating child seat installations have become a familiar rite of parenthood," says Jessica Jermakian, an IIHS senior research engineer. "Unfortunately, these frustrations lead to mistakes that can have real consequences in the event of a crash. We're pleased to see automakers taking this issue seriously and making improvements in response to our ratings."

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The IIHS ratings only take into account the ease of properly installing a child safety seat; they do not address the performance of those systems in case of a crash. A car seat properly installed using a difficult-to-use LATCH system is just as safe as one installed in an easy-to-use configuration.

There are two components to LATCH: a pair of lower anchors that your car seat clips into and a place for an upper tether to attach. The lower anchors are located where the seatback and seat bottom meet. Some are easier to access than others, with some located so deep in the crevice that they’re hard to find. Top tethers can be located on the back of the seat, on the load floor of SUVs and crossovers, on the rear deck behind the back seats of sedans and coupes, or on the ceiling in some vehicles. In IIHS ratings, tether locations on the upper 85 percent of the seatback or the rear deck are rated higher than those on the floor, ceiling, or far down on the seatback.

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IIHS testing also looks at how much force is necessary to install a car seat to the lower anchors, as well as the flexibility of the lower anchors. Proper labeling is critical, and it is also included in the IIHS criteria.

Vehicles tested fall into one of five categories: Good+, Good, Acceptable, Marginal, and Poor. There’s no correlation between vehicle size or price when it comes to success in the rankings. In fact, the 2016 vehicles that ranked at the bottom came from a variety of segments. Those vehicles earning a Poor ranking include the Chevrolet Silverado 1500 crew cab, GMC Sierra 1500 crew cab, Infiniti QX50, Ford Fiesta (sedan and hatchback), Hyundai Accent hatchback, Infiniti Q70, and Subaru BRZ.

Ratings can vary within the same models, as differences in seat materials and seating designs can be found with different trim levels. IIHS has worked to include as many of those variations as practical in their ratings, according to spokesman Russ Bader.

Before you buy a car to haul around your precious cargo, check out our car seat buying advice, learn how to avoid the most common car seat mistakes, and get the most out of your car seat. Catch the latest car buying advice by following the expert staff of U.S. News & World Report on Facebook and Twitter.