Mercedes-Benz GLA45 AMG: High-performance on half the cylinders

The Mercedes-Benz AMG high-performance shop takes big sedan and SUV models from the German automaker, replaces the engines, transmissions and suspension components, and ends up with luxury muscle cars. AMG engineers hand-build the V-8 and V-12 engines, adding a signature plate onto each.

The division set an impressive standard with cars such as the CLS63 AMG and the G63 AMG , but can Mercedes-Benz extend AMG characteristics to its newer, smaller cars? I decided to seek the answer to that question when I got a chance to drive the 2015 Mercedes-Benz GLA45 AMG on the Mazda Raceway at Laguna Seca.

The GLA45 AMG is based on the GLA250 , a new compact SUV from Mercedes-Benz. Both models use a 2-liter four cylinder engine with a turbocharger and direct injection, so at first glance it may seem like Mercedes-Benz merely added an aero kit and suspension tweaks to create this new AMG. The specs, and the driving experience, tell a different story.

2015 Mercedes-Benz GLA45 AMG
The Mercedes-Benz GLA45 AMG tackles the corkscrew at Mazda Raceway Laguna Seca. Antuan Goodwin/CNET

The AMG shop managed to turn the output up from 208 horsepower in the GLA250 to 355 in the GLA45 AMG, which also boasts 332 pound-feet of torque. With upgraded turbo, injection system, programming and exhaust, this small engine becomes so potent that Mercedes-Benz Chairman Tobias Moers called it "the world's most powerful series-production four-cylinder engine" when the car was unveiled in September, 2014.

I liked the look of the GLA250, but I liked the GLA45 AMG, coated in Jupiter Red and sitting in the Laguna Seca paddock, even more. The grille sported the AMG "twin-blade" horizontal bar supporting the Mercedes-Benz badge, red-painted brake calipers screamed performance and a wing over the hatch was sculpted with side vanes. On closer inspection, I noticed the flics, little aero elements, mounted low on the front fenders, channeling air out of the wheel wells, suggesting the aero engineering was more than cosmetic.

And lifting the hood, there on the too-small engine's cover was a plate inscribed with the builder's name, further proof of its AMG pedigree.

Full throttle on the straights

Firing it up, I didn't hear the joyful bark of the larger AMG engines, just an initial growl followed by a quiet idle. During my first set of laps, I used the steering wheel-mounted paddles to manually choose my gears from the seven-speed dual-clutch transmission, then opted for the automatically shifting sport program on my final set. This shifts were as responsive as I could have wanted, but the power blips were muted. Instead of a massive torque jolt in the car from changing revs the gear changes were very smooth. Maybe chalk that up to proper braking, getting the speed right before each gear change.

2015 Mercedes-Benz GLA45 AMG
On any straight at Laguna Seca, I could hit full throttle in the GLA45 AMG. Wayne Cunningham/CNET

Flooring it on the main straight, I shifted through third, fourth, fifth, each near-redline gear change producing a delightful blat-blat from the exhaust, a sound that helped the GLA45 prove its AMG-worthiness. During my laps with the sport program doing the shifting, the car mimicked my gear changes, although was smart enough not to hit the rev limit, which I did once or twice. Despite the 355 horsepower from this engine, I found the need to shift up to fourth on most of Laguna Seca's straights, going all the way up to fifth on that main straight.

Higher-bodied than a typical sports car, I wasn't surprised to feel some lean in the corners, but the tight suspension and added stabilizer bars mostly kept it under control. Unlike the bigger AMG models and their adaptive suspensions, the GLA45 has to get by with a fixed suspension. I can't comment on how it might feel on rough, pothole-strewn pavement, but it felt solid and even comfortable on the track.

The steering felt responsive, reacting minutely to my inputs. As with other electric power steering systems, I didn't feel it fight me at all, instead following my inputs with no fuss. In the turns, I could feel the GLA45 AMG rotate like a hot hatch, letting me enjoy this tossable little car. And when I began to wonder how much grip it had left, I recalled that this little AMG comes standard with all-wheel-drive, so I could give it more throttle and gain more traction. The all-wheel-drive system here is front-wheel-biased, but will switch to a 50:50 front/rear split when holding the road becomes important.

2015 Mercedes-Benz GLA45 AMG
You can seen the GLA45 AMG lean just a bit as it goes through the Andretti hairpin. Antuan Goodwin/CNET

At Laguna's turn 2, the Andretti hairpin, that grip became very important as I twisted the GLA45 AMG around looking for the second apex and feeling a four-wheel slide towards the outside edge of the track. But the power pumping out to all four wheels and the wide tires dug in enough to fight the angels of inertia and carry me through the turn exit.

Expanding AMG

At day's end, I could say I enjoyed the hell out of the GLA45 AMG and would gladly lap it again and again to explore its capabilities further. However, I also took a Mercedes-Benz CLS63 AMG around the track that day in between sessions with the GLA45 AMG. With its twin-turbo 5.5-liter V-8 producing 577 horsepower, it far out-powered the GLA45 and felt like a proper product of AMG. The radically different feeling in the turns, refined control for the CLS63 and hot hatchback twistiness in the GLA45, also shifted my perspective of whether the AMG logo was properly applied.

Ultimately I decided that the GLA45 AMG was not what I've come to expect from AMG, but it certainly has qualities that helped broaden my mind to what AMG can become.