2007 GMC AcadiaClick to enlarge picture

The Acadia is GMC's newest model and it shares the same chassis, transmission and engine with the Saturn Outlook and Buick Enclave.

Indeed, automakers project that crossovers—many of them midsize—will become the darlings of consumers and quickly outsell traditional, truck-based SUVs.

You see, crossovers use car foundations or underlying platforms that are more like cars than trucks. This helps the vehicles ride more smoothly, like cars than the traditional, truck-based SUVs. Crossovers can be lighter weight and more fuel-efficient than traditional SUVs, too. But they still seat passengers higher above the pavement than a regular car to provide improved visibility.

Be warned, however. On the outside, crossovers tend to be styled to look like SUVs, so it's not always easy to tell what you're looking at. Examples of midsize crossover vehicles include the Toyota Highlander, Buick Enclave, GMC Acadia and Ford Edge. Meantime, midsize SUVs with truck platforms include the likes of the Nissan Pathfinder, GMC Envoy, Ford Explorer and Dodge Durango.

Photo Gallery: Midsize Sport-Utility Vehicles

Note that crossovers, even if offered with all- or four-wheel drive, tend to be designed for on-pavement/on-dirt-road duty. Truck-based SUVs, especially if they have a low gear, can do both on-pavement and strenuous off-road-terrain chores and generally provide superior towing capacity.

The midsize crossovers and regular SUVs are the biggest SUV segment overall in America. Tallied together, there are some four dozen midsize SUVs and crossover SUVs on sale in the U.S., and all are featured on MSN Autos. Starting manufacturer's suggested retail prices range from just over $21,000 for a two-wheel-drive Hyundai Santa Fe with 185-horsepower V6 to more than $93,000 for a Porsche Cayenne with 500-horsepower, turbocharged V8.

Newest Models
The newest models include GMC's Acadia with its two other siblings from General Motors Corp.—the Saturn Outlook and the Buick Enclave. All use the same, new chassis, six-speed automatic transmission and 275-horsepower V6. Stretching more than 16 feet long, from bumper to bumper, these vehicles are about as long as GM's minivans and carry three rows of seats, like the minivans. In fact, the Outlook and Enclave already have replaced the Saturn Relay minivan and Buick Terraza minivan, because production of these minivans ended during the 2007 model year. GMC, better known for pickup trucks, never had a minivan, and a Chevrolet crossover is expected in calendar 2008, at which time Chevy plans to drop its Uplander minivan.

Compare the Saturn Outlook, Buick Enclave and GMC Acadia

Toyota's Highlander is revamped as a larger crossover SUV starting in summer 2007. The 2008 Highlander rides on a new platform derived from the Toyota Camry and Avalon sedans and is nearly 4 inches longer and 3 inches wider than its predecessor. This improves interior room, particularly in the third-row seat. There's no longer a 4-cylinder engine, just a more powerful V6 generating 270 horsepower.

The 2008 Highlander Hybrid gets the same, improved interior and 270 horsepower but it comes from a newly refined gasoline-electric hybrid powerplant. Best of all, despite the increased power, the government fuel economy rating is to remain at 31 miles per gallon in city driving and 27 mpg on the highway, which is the same as the lower-powered, 2007 model. (Yes, the supplemental electric power aids city mileage more than it does highway mileage.)

The new Highlander Hybrid also includes a first-ever, selectable, all-electric mode that a driver may activate with a push of a button inside the vehicle. This allows quiet, electric-only propulsion at low speeds for short distances, provided the engine and battery conditions allow it.

Porsche's only SUV, the Cayenne, is a restyled, more powerful, second-generation model for 2008. All three Cayenne engines now get direct fuel injection for more efficiency and power. The top, twin-turbocharged V8 puts out 500 horsepower, and there are new, high-tech features including headlights that turn around curves, rollover sensor and XM satellite radio. For the first time, Porsche offers 21-inch wheels for the Cayenne as well.

Subaru's largest SUV, the B9 Tribeca, is revamped for 2008. Most prominently, the front end that had been criticized by some as unattractive, is changed for a more mainstream appearance. There's a new, more powerful, 3.6-liter boxer 6-cylinder engine mated to a revised 5-speed automatic transmission. Together, they provide 256 horsepower and 247 lb-ft of torque. Inside, third-row seating is improved and there are additional convenience features.

Watch later in calendar 2007 as Infiniti adds a slightly smaller crossover SUV to its lineup. The 5-passenger, 2008 EX promises less masculine styling than the Infiniti FX has—more along the lines of the Lexus RX 350—and V6 power.

Hybrid Power
In the midsize sport-utility segment, there are two vehicles with gasoline-electric hybrid power. Both are from Toyota Motor Corp.: the Toyota Highlander Hybrid and Lexus RX 400h.

Improved fuel economy and reduced emissions are among the benefits of these hybrids. For example, Toyota already is calling the 2008 Highlander Hybrid the "most fuel-efficient midsize SUV" in America even with fuel economy ratings being recalculated under a stricter formula for the 2008 model year.

Read:  Read more about 2008 fuel economy ratings revisions

Most other midsize sport utilities use traditional gasoline internal combustion engines as their sole power sources. Typically, the engines have either six or eight cylinders. Hummer's first midsize sport utility, the H3, and Volvo's XC90 feature five-cylinder engines.

Reasons to Consider Midsize SUVs
Key reasons for the popularity of this class of SUV are the size and room of these vehicles. Generally, they're not as small as compact SUVs, and they're not as big as full-size sport utilities. Thus, they're viewed by consumers as the "middle choice." For example, the midsize Jeep Grand Cherokee stretches 15.5 feet long, from bumper to bumper, and offers a decent 35.5 inches of rear-seat legroom. This compares with the Chevrolet Suburban, that's larger than the Grand Cherokee at 18.5 feet long and has 39.5 inches of room in the second-row seats as well as a full 34.9 inches for third-row passengers.

In recent years, several midsize SUVs have added third-row seats in an effort to better appeal to active families. The Ford Explorer, Nissan Pathfinder and Toyota Highlander are among the models with this feature.

Buyers would do well to compare these third-row seats carefully to judge seat comfort for themselves, however. For example, the Pathfinder provides 28.1 inches of legroom in the third row. This compares with 34.9 inches in the third row of the Explorer and 31.5 inches in the third row of the Hyundai Veracruz.

With five-, six- and eight-cylinder engines available, midsize sport utilities can serve as quite capable towing vehicles. For example, the Toyota 4Runner can tow 7,300 pounds when fitted with an uplevel, 260-horsepower 4.7-liter V8. This is nearly as much towing capacity as some full-size SUVs. But midsize SUVs that have smaller engines and/or are car-based can have lower towing limits. An example: The Veracruz with 260-horsepower 3.8-liter V6 can tow a maximum 3,500 pounds.

Read:  Read more about the 2007 Hyundai Veracruz

All midsize SUVs are offered with four- or all-wheel drive, which can provide extra traction in some road conditions and help carry a family to a winter cabin or to a summer camping trip. Buyers also tend to like the higher ride height that they get with these SUVs compared to cars.

Fuel economy of midsize SUVs can be better than that of the larger, heavier SUVs. For example, the 5-passenger Lexus RX 350 with two-wheel drive is rated at 18 miles a gallon in city driving and 23 mpg on the highway as a 2008 model. This compares with the 2008 rating of 12/18 mpg given to the V8-powered Nissan Armada full-size SUV with two-wheel drive.

Some Disadvantages
Don't let the term "midsize" fool you. Some midsize SUVs, especially with V8s, can get fuel economy ratings that are more like those for bigger SUVs. For example, the midsize 2008 Porsche Cayenne with the up-level twin-turbo V8 is rated at 12/19 mpg, which is more akin to a large SUV than a smaller one. Also note that the recommended fuel for many high-performance midsize SUVs is the costlier premium unleaded.

Midsize SUVs have become pricey over the years. Many are priced higher than mainstream family sedans. For example, Hyundai's Veracruz has the highest starting price of any Hyundai at more than $26,000. This is more than the $24,000-plus starting price for the luxury-appointed Hyundai Azera midsize sedan.

Cargo space in some midsize SUVs may not be as expansive as some buyers expect. The midsize Grand Cherokee's maximum cargo space is 67.4 cubic feet when rear seats are folded down. This is less than the 70.1 cubic feet found in the compact Honda Element SUV when the Element's rear seats are folded down.

It can be a big climb up to get into some midsize SUVs. Step-in height, for example, on the Hummer H3 is at least 2 feet. The H3 looks like a Hummer, with its aggressive, boxy styling. But the vehicle rides on the platform of the Chevrolet Colorado pickup truck.

Sibling SUVs Found Here
Many midsize SUVs are versions of other SUVs. For example, Buick's midsize Rainier and Saab's first SUV, the 9-7X, are versions of the Chevrolet Trailblazer and GMC Envoy.

Ford's Explorer has a sibling midsize model called the Mercury Mountaineer. And the Honda Pilot evolved out of the Acura MDX.

More Sophisticated Features, More Power
With each passing year, midsize sport utilities add more power and sophisticated features. For instance, the second-generation Mercedes-Benz M-Class was the first SUV in the world with a standard 7-speed, automatic transmission. It improves both fuel economy and responsiveness when compared with transmissions that have fewer gears.

Land Rover's LR3 was the first SUV with a patented Terrain Response system that allows a driver to optimize control and traction by selecting, via a rotary knob, the kind of conditions the vehicle is traveling on. The vehicle automatically adjusts the engine torque response, vehicle ride height and other items, according to the driver's description of the terrain.

Increasingly, buyers can find substantial engine power in the midsize SUV segment. For instance, Volvo now sells a version of its midsize SUV, the XC90, with a 311-horsepower 4.4-liter naturally aspirated V8. It's the most powerful Volvo passenger vehicle in history. Chevy's TrailBlazer now has an SS model with 395-horsepower 6.0-liter LS2 V8. And Jeep's Grand Cherokee gets more power and quickness than ever with the addition of a 420-horsepower 6.1-liter HEMI V8. The model is known as the Grand Cherokee SRT8.

In the market for a new car? MSN Autos is pleased to provide you with information and services designed to save you time, money and hassle. Click to research prices and specifications on any new car on the market or click to get a free price quote through MSN Autos' New-Car Buying Service.