2013 Geneva Auto ShowJust the Facts:
- Mercedes AMG will unveil its first four-cylinder in 45 years at the upcoming Geneva auto show.
- The A45 AMG's 2.0-liter turbo pumps out 355 horsepower at 6,000 rpm.
- Torque is rated at 332 pound-feet.
GENEVA — Mercedes-Benz will be entering an entirely new world when it debuts the A45 AMG at next month's 2013 Geneva Auto Show.
The default AMG response to any question or threat has always been to pile on more power. That has served it well with blacktop-bludgeoning V8s, but the definition of a great hot hatch is a very different one. It's a world where the engines of the best offerings don't stand out as much as the balance and poise of the chassis package.
Having given a select few media outlets a ride in the A45 a couple of months ago, AMG has finally announced the official details — and the numbers are every bit as impressive as Development Boss Tobias Moers promised.
The A45's 2.0-liter turbo pumps out an incredible 178 horsepower per liter to arrive at 355 hp at 6,000 rpm. It's torque-rich, too, with the 1,991cc undersquare four-pot delivering 332 pound-feet at just 2,250 rpm and holding that in a plateau until 5,000. It also still revs to 6,700 rpm and weighs 326 pounds fully dressed.
The result is a thumping 4.6-second sprint to 62 mph and it's so enthusiastic at the top end that it is reined in by a speed limiter at 155 mph.
"The A45 AMG will enable Mercedes-AMG to appeal to new customers and tap new markets," AMG Chairman Ola Källenius said. "We are adding an extremely attractive model with exceptional performance data to our range of unique high-performance automobiles."
And the A45 won't be the last of it, because it will also show the even sportier CLA45 AMG at the 2013 New York Auto Show in late March. While the A45 will be kept away from North America, the CLA45 will be a truly global hotshot four-pot.
One senior executive from a rival German tuner said it was one thing to push huge horsepower per liter out of a racecar, but admitted AMG had moved the game on and provoked a specific-power war with the A45's engine.
That admission was music to the ears of Tobias Moers, who proudly insisted: "With the A45 AMG we have well and truly achieved our aim of developing the most dynamic, powerful and efficient four-cylinder series production car."
To do all this, the A45's twin-scroll turbocharger runs up to 26 psi of boost pressure along with direct injection via centrally located piezo injectors. These deliver multiple injections, backed up with multiple sparks per ignition for clean burning and massive power.
AMG builds the engine on its own assembly line at Benz's Kölledo plant in Germany. That means it's built under the same roof as all of the A- and B-Class gas engines, but it's a lot more complicated than they are, even if it shares the bore and stroke dimensions of the base 2.0-liter.
Its block and crankcase are both sand cast and it offers tougher, lighter bits like forged pistons, a forged steel crankshaft and sodium-filled valves.
The A45 AMG uses a big-bore exhaust system, complete with muffler-bypass flaps for more noise and energy, and finishes with a pair of chromed AMG exhaust tips.
There is also a huge front water-to-air intercooler with a supplementary cooler in the front wheel arch, while the transmission cooler is built into the main radiator and has its own supplementary heat exchanger attached directly to the transmission.
All this power was always going to overwhelm the A-Class's front-drive chassis architecture, so AMG fitted the A45 with 4Matic all-wheel drive that can be split 50/50.
Power will run through a dual-clutch seven-speed transmission that uses software adapted from the SLS's seven-speed dual-clutch tranny (its shift times in both Sport and Manual modes are just as fast as the SLS's) and includes three software maps for different driving intensities.
The A-Class usually runs as a front-driver, but can send up to 50 percent of its performance to the rear axle in an instant. That's because the rear diff contains a multidisc clutch pack that's fed by a two-piece prop shaft, and the hydraulic pump controlling it is constantly driven. Unlike other part-time all-wheel-drive systems, that means the A45 doesn't have to wait for the computer to switch the rear diff's hydraulic pump on.
The suspension, too, is barely recognizable as an A-Class item. It uses a three-link front end with stiffer bearings, while a four-link rear end scores stiffer bearings and new struts.
It all rides on 235/40 R18 rubber at all four corners, with 13.8-by-1.3-inch front discs and 13-by-0.9-inch rears, though there is an optional 235/35 R19 wheel and tire package.
It's also much more focused inside, with aggressive AMG seats, steering wheel, pedals and switchgear supplementing the clean, modern A-Class interior package.
Edmunds says: AMG is out to prove that a four-cylinder, front-wheel-drive hatchback can still form the basis for a serious performance car.