Midsize suvs are sort of the navel of the automotive world: Just about every mass-market company has one. In fact, some have two, or even three.

That’s probably because midsize models were long the biggest-selling segment in the SUV market. Today there are 18 in the class, actually down a bit from their peak. Most are “crossovers”: high-riding wagons offering all-wheel drive but built on passenger-car platforms.

Only a couple are of the old truck-type body-on- frame design. The latter often have higher towing limits, and are sometimes aimed more at off-road driving.

All models in this class offer all-wheel drive or 4-wheel drive, the latter sometimes available in part- and full-time versions. With all-wheel drive, it’s always engaged and the vehicle decides whether power should go to all four wheels. With 4-wheel drive, the driver can choose between 2-wheel drive or 4-wheel drive. Some Toyota 4Runner models offer a part-time 4-wheel-drive system, which is intended for severe off-road work and cannot be left engaged on dry pavement for fear of driveline wear. That’s not a concern with full-time 4-wheel drive.

WHAT’S NEW FOR 2017

The midsize crossover/SUV class sees two redesigned vehicles for 2017: the GMC Acadia and Mazda CX-9. Well, technically the Mazda CX-9 is a 2016 model, but it launched late enough in the season that it is on sale alongside 2017 models—and we doubt there will be any significant changes for its 2017 model-year season. The new CX-9 is powered by a turbocharged 2.5-liter 4-cylinder that makes 227 horsepower on regular gas and 250 hp on premium. A host of new safety and technology features is available, along with a new line-topping luxury-grade trim level named Signature. The new GMC Acadia retains its available third-row seat, but is significantly smaller than its predecessor—it’s almost four inches narrower, seven inches shorter, and about 700 pounds lighter. The trimmer dimensions put the Acadia more in the heart of the midsize crossover segment. A 193-hp 4-cylinder engine is added the powertrain lineup, joining the previously standard 310-hp 3.6-liter V6.

The Nissan Pathfinder is significantly updated with revised styling and a freshened interior; an updated engine with a bit more horsepower (284 hp instead of 260); and newly available technology features such as adaptive cruise control, automatic emergency braking, a surround-view camera, and a hands-free liftgate. The top trim level of the Chevrolet Equinox and Traverse is now named Premier instead of LTZ; the Equinox adds a couple of appearance packages and the Traverse has a new LS Base model. The Dodge Journey’s top trim level is now named GT instead of R/T. The Ford Explorer gets a Sport Appearance Package for the XLT model, and the unloved MyFord Touch infotainment system is replaced by Ford’s Sync 3 interface.

The GMC Terrain adds a Nightfall Edition appearance package on SLE-2 and SLT models. The Jeep Grand Cherokee gets a new off-road-oriented Trailhawk model, and the Summit trim level has revised interior and exterior styling. The Kia Sorento adds Apple CarPlay and Android Auto functionality, and the SXL model now comes only with a V6. The Toyota 4Runner adds rugged TRD Off-Road and TRD Off-Road Premium trim levels. Information on the 2017 Ford Edge, Ford Flex, Honda Pilot, and Nissan Murano was not available as of this writing, but we don’t expect any major changes.

MODELS THAT OFFER SOMETHING UNUSUAL

The only vehicle that stands out in that regard is the Jeep Grand Cherokee. It’s the sole vehicle in the class to offer a V8 engine, and its high-performance SRT version has an even more powerful V8 engine. Grand Cherokee also offers the class’s only diesel engine.