When the Ford Explorer was significantly upgraded for 2006, the similar Mercury Mountaineer was given the same treatment, bringing both of these popular SUVs up to date.

For 2007, there are some additional improvements, including the addition of Ford's Safety Canopy side-curtain air bags as standard equipment, an important safety feature in a large sport utility as this. The side curtain air bags offer great protection to the vehicle's occupants in the event of a rollover.

The vehicle also comes with electronic stability control system, made standard last year. This feature is designed to help prevent a rollover accident in the first place - always the better option than trying to survive an accident of this sort.

New amenities for 2007 beyond the safety features include an optional GPS navigation system and power-operated running boards ($695), which give passengers an easy way to step into or out of the vehicle.

When the doors are opened, these running boards, which were included on our test vehicle, come out automatically.

Two versions of this midsize sport utility are offered for 2007 - the base Mountaineer and the Premier model, which we tested. Both are offered with either rear- or all-wheel drive.

The Premier model is available with either a V-6 or a V-8 engine, while the base model comes with only the V-6.

The Mountaineer continues on the same chassis as the Explorer and is essentially just a dressed-up version of Ford's long-running sport utility vehicle.

The base Mountaineer begins just under $28,000. It uses the same 4.0-liter V-6 engine that powers the base Explorer, rated at 210 horsepower.

As in the Explorer, the V-6 engine is connected to a five-speed automatic transmission. Ford says this engine was improved last year to deliver better fuel efficiency and lower tailpipe emissions without any loss of power.

The starting price is about $3,000 more than that of a base Explorer. The higher price of the Mountaineer reflects the extra content that is not included in the entry model Explorer.

Our test vehicle, though, was a bit more pricey, as we had the Premier model with the optional V-8 engine and fulltime all-wheel drive (base price $33,840 plus $695 freight).

It comes with the same new 4.6-liter V-8 as the Explorer, as well as the new six-speed automatic transmission introduced last year - a first in this market segment where the standard had become a five-speed automatic.

With a few extras tacked on, our tester's sticker price was $39,165 (including freight), but that included just about everything available.

The V-8 delivers 292 horsepower and 300 foot-pounds of torque, quite an improvement over the 239 horsepower and 282 foot-pounds of torque of the 2005 model's 4.6-liter V-8.

With either engine, EPA ratings are 15 miles per gallon in the city and 21 on the highway with two-wheel drive. With all-wheel drive, the ratings are 15 city/20 highway with the V-6, and 14/20 with the V-8.

The Mountaineer benefits from all of the improvements to the Explorer, including a much quieter interior that delivers probably the first truly carlike ride yet from these truck-based SUVs.

Of course, the Mountaineer also got the same safety improvements that came in the new Explorer, including side-impact protection that meets U.S. standards required through 2010.

Other safety features include front seat-mounted side air bags, an energy-absorbing steering column, front air bags with an automatic occupant classification system, adaptive safety belts, and a new tire-pressure monitoring system.

The extensive safety improvements with the redesigned Explorer and Mountaineer that debuted for 2002 have made these among the safest SUVs on the market, and the changes last year and for 2007 build on the earlier improvements to help make the vehicles even safer.

Because the Mountaineer is positioned as an upscale version of the Explorer, last year's changes brought a new premium interior. The company is particularly proud of the improvements that help to reduce noise, vibration and harshness and make the cabin of the Mountaineer a more pleasant place at highway speeds.

"Reduced climate-control-system noise, carpets and headliners constructed from advanced, lightweight sound deadening materials, and rearview mirrors designed for better visibility and lessened wind noise all combine to offer Mountaineer's occupants the quietest ride in the midsize SUV segment," Ford said.

Among other interior improvements were new seats, door trim and instrument panel. The interior trim has a satin-aluminum finish that gives the vehicle an elegant look without being gaudy.

Seating configurations allow the vehicle to hold up to seven passengers or a combination of fewer passengers and more cargo.

The second row of seats is available in three different configurations. The base model has a 60/40-split/fold-flat second-row bench seat. The Premier model also comes with a 60/40 bench, but it has reclining seat backs to allow access to the third row, which is standard on the Premier. Second-row bucket seats with a center console are optional on either model.

As with the Explorer, there is an optional power-folding third seat that allows it to be put away into the floor at the push of a button. This feature is standard on the Premier model, and is a great improvement over manually folding seats or the seats found in some minivans and SUVs that have to be removed to create extra cargo space.

Unfortunately, with the third seat in place, there isn't much cargo space. But with the third seat folded into the floor, there is a large, flat load space. If the second row isn't needed, that seat can be folded down to increase cargo capacity dramatically.

In keeping with Mountaineer's upscale image, the seats are leather trimmed and the driver's seat has a 10-way power adjustment.

Eighteen-inch aluminum wheels, a rear parking-assist system, heated front seats, and a keyless-entry system that includes a keypad on the driver's door are standard on the Premier.

Also standard on our Premier model were dual front automatic climate control and an auxiliary climate-control system for the rear.

An Audiophile AM/FM/compact disc stereo system is standard on the Premier. It includes an in-dash, six-disc CD changer (with MP3 playback capability) and eight speakers.

The Mountaineer differs from the Explorer when it comes to four-wheel drive. While the Explorer offers a true off-road-capable four-wheel-drive system with two-speed transfer case for low-range gearing, the Mountaineer offers only a fulltime all-wheel-drive system that does not include a transfer case with low range.

The system adds $2,275 to the price of the Mountaineer at any trim level. It gives the vehicle limited off-road capability, but allows for better traction in bad weather. If you're looking for an SUV to take into the wild, though, this is not the one.

A heated windshield is offered in all models for 2007, Ford says, although that's not a system in great demand in Texas.

Aficionados of the iPod will enjoy the new auxiliary audio input jack on the 2007 model, which allows for connection of the iPod or other MP3 player to the vehicle's audio system.

Also offered this year are Sirius satellite radio ($195); an improved rear-seat DVD entertainment system ($1,295) with an eight-inch screen that folds down from the middle of the ceiling in front of the middle seat; and a GPS/DVD navigation system packaged with a power moon roof ($2,845). These were among the extras included on our tester, along with power adjustable pedals ($225) and a towing package ($225). A discount on our Premier model took $850 off the price of the navigation/moon roof option.

G. Chambers Williams III is staff automotive columnist for the San Antonio Express-News and former transportation writer for the Star-Telegram. His automotive columns have appeared regularly in the Star-Telegram since 1995. Contact him at (210) 250-3236; chambers@star-telegram.com.

At a Glance: 2007 Mercury Mountaineer

The package: Midsize, rear- or all-wheel-drive, four-door, five-, six- or seven-passenger, V-6 or V-8 powered, truck-based sport-utility vehicle. Highlights: Heavily redesigned last year, this is the latest generation of the Mercury clone of the Ford Explorer. It rides on a new frame, and is more refined than the vehicle it replaced; it also has more towing capacity and a quieter ride. Negatives: Limited cargo space behind third seat; all-wheel drive not suited for rugged off-road use. Engine: 4.0-liter V-6, 4.6-liter V-8. Transmission: Five-speed automatic (V-6); six-speed automatic (V-8). Power/torque: 210 HP/254 foot-pounds (V-6), 292 HP/300 foot-pounds (V-8). Length: 193.5 inches. Base curb weight: 4,457-4,717 pounds. Fuel capacity/type: 22.5 gallons/unleaded regular. Cargo capacity: 13.6 cubic feet (behind 3rd seat); 43.9 cubic feet (behind 2nd seat). Towing capacity: 5,200-7,220 pounds, depending on configuration and engine. Brakes: Disc/disc, antilock. Safety: Electronic stability control and side-curtain air bags standard. EPA fuel economy: 15 city/21 highway (2WD, V-6 or V-8). Base price range: $27,300-$33,840 (plus $695 freight). Price as tested: $39,165 (Premier V-8 model with all-wheel drive, including freight and options, such as navigation and rear DVD). On the Road rating: 8.2 (of a possible 10).