Mercedes-Benz

Being suddenly confronted by a charging canine, incisors bared and in full bark mode seemed totally out of place with the pastoral Vermont scenery.

Yet there the big beast was, guarding the apex of a sharp right-hander on one of the state’s winding secondary highways.

In an instant, the GLA45 AMG’s beefy brakes went to work bringing the newest member of Mercedes-Benz’s tall-wagon family down to an abrupt stop.

Refusing to yield ground, the pouncing pooch just kept on snarling while steadily advancing toward the AMG, as if planning to devour it. Eventually, it backed down, leaving the Mercedes as the undisputed king of the road. Yes, the GLA was gracious in giving way (although its driver remained slightly agitated). That would be the only instance it would do so during two days of traversing the picturesque highways and byways of northwestern New England.

In many ways, the dog and the AMG have much in common. Both wagon and canine are a breed apart from the rest of the pack; both possess sufficient muscle and bark to make their presence felt. The GLA45 AMG appears to have more bite.

It’s the more potent derivative of the GLA-Class family of two that includes the tamer GLA250. These wagons share much of the new-for-2014 CLA sedan’s architecture and drivetrain, including its all-wheel-drive system that’s an option on the CLA, but standard-issue on the GLA and the AMG variant.

That base GLA250, although hardly “base” in any real sense of the word, is equipped with a turbocharged 2.0-liter four-cylinder engine that generates a modest 208 horsepower and 258 pound-feet of torque. However, the AMG’s 2.0-liter four-cylinder steps up to the tune of 355 turbocharged horsepower and 332 pound feet of torque.

Why so large a disparity between two seemingly similar engines?

Well, although the displacements are equal, the AMG’s engine block has been strengthened and its higher-output turbocharger produces nearly twice the boost of the GLA250’s. Lacking a stopwatch, or even enough of a straight line well off Vermont’s beaten track (otherwise called Highway 89) to properly evaluate the AMG’s acceleration, Mercedes-Benz’s testing indicates a zero-to-60-mph time of 4.8 seconds, which is significantly quicker than the GLA 250s 7.1-second time.

The sole transmission is a seven-speed automated manual transmission with paddle shifters that bangs off rapid up-shifts and rev-matched downshifts. In Sport mode. the AMG’s shift points are firmed up, the exhaust note gets much louder and a temporary ignition interruption between up-shifts creates a cool backfire “blatting” noise that’s reminiscent of a Formula One race car.

All GLAs have M-B’s 4MATIC all-wheel-drive that’s tuned specifically for the AMG. During normal driving, the torque is biased to the front wheels, however can be sent to the rear wheels, as needed.

Of course, for horsing around Vermont’s twisties in the fall, or anywhere at any time of year, the AMG version is a standout. The well-insulated (and luxurious) cabin is hushed enough for all aboard to ingest the passing splendor of the countryside in quiet reflection, at least for short periods.

Then the urge to turn up the wick invariably kicks in and the snaky two-lane beckons you to drop the proverbial hammer.

The AMG’s suspension is turned to a firmer setting, but not so as to become jittery or jarring over uneven surfaces. In addition, the car’s stability control with Dynamic Cornering Assist improves front-axle traction in tight turns by applying slight braking force on the inside wheels. The result is less steering effort and improved directional stability.

The tab for all this good-natured fun starts at $49,200, including destination charges, but rises rapidly with the addition of one or more tempting option packages.

Ultimately, what sets the AMG apart are its good looks, practicality and stout mechanicals that, unlike some auto-eating canines, remain under your command at all times.