Two different powertrain choices are offered in the 2010 Mercury Mountaineer. The 4.0-liter V-6 brings adequate performance, but it's a little too coarse and rough. The available 4.6-liter V-8 provides better performance with a smoother character and real-world fuel economy that's almost as good. The V-6 comes with a five-speed automatic, and the V-8 is equipped with a six-speed automatic transmission. Both are available in rear- or all-wheel-drive versions.
Car and Driver says "the V-8 is tons of fun in the Mustang GT, where it feels like there's an offensive lineman on meth under the hood, but in the [Mercury] Mountaineer, it's pretty snooze-worthy," although this reviewer notes "you'll definitely be able to put it to work, with a 6960-pound tow rating in all-wheel-drive V-8." In regard to the smaller engine, Edmunds comments that the Mercury Mountaineer's "210-horsepower V6 looks more underpowered with every passing year."
The transmission isn't as responsive as many reviewers would like. Edmunds reports that it's "a bit slow to downshift." Car and Driver elaborates: "downshifts all happen at their own pace; there's no sense in asking any of them to hurry, because the Mountaineer will just ignore you." The Mountaineer comes with rear-wheel drive standard, but there is an optional all-wheel-drive system available.
Gas mileage isn't very impressive with either engine, but TheCarConnection.com notes similar mileage between the two. Ratings are as low as 13 mpg city with the V-6 (the more efficient of the two engines) and AWD. Many of the newer car-based crossovers will do much better. ConsumerGuide states "an AWD V8 Mountaineer averaged 15.1 mpg."
Overall, the Mountaineer feels like a truck, but it's smooth, stable, and responsive for something that weighs 5,000 pounds. The Mercury Mountaineer's "independent rear suspension provides it with great stability while cornering and the variable-rate power steering returns excellent feedback to the driver," says ConsumerGuide. And according to Edmunds, "brakes, though adequate when it comes to stopping, have a spongy pedal feel."