The Mercedes-Benz A45 AMG 4 Matic opens a new
chapter in performance efficiency
AMG’s decision to take the four-cylinder
route was, no doubt, met with a good deal of scepticism by those enamoured with
the firm’s fire-breathing V8 and V12 models, but there is one thing to bear in
mind. The fact that the vessel for this new powerplant would be based upon the
company’s smallest offering, the striking new A-Class, may have softened the
blow a bit.
The hesitant will, no doubt, eat their
words when confronted with the attestation; at the heart of the A45 AMG lays
the most powerful series-production four-cylinder engine in the world. Simple.
No argument. But there’s more than just class-leading power at play here. In
many respects, the A45 represents the first wave of a sea change that sees the
future of thrilling yet efficient performance meet the traditional sporting
ethos of Affalterbach’s fi nest.
The
A45 AMG 4 Matic is a sharply styled hatchback
The 265 kW and 450 Nm of torque that the
A45 AMG’s 2.0-litre turbocharged powerplant develops are, in themselves,
impressive, as they constitute outputs previously unheard of in its class. But
what’s perhaps even more astonishing is this engine’s power density, the
output-per-litre of engine displacement. You’ll be hard pressed to find
anything that yields the A45’s 133 kW/litre.
One of the perennial challenges regarding
small-displacement, turbocharged engines is that of turbo lag. To this end,
AMG’s engineers have utilised a twin-scroll turbocharger with a maximum-charge
pressure of 1.8 bar combined with high-pressure fuel injection and the maximum
allowable derestriction of the exhaust system. The upshot is greater low-end
torque and more linear power delivery that banishes lag off the line.
The
black dials with carbon fibre-effect inserts are one of the A45's
distinguishing features
Factor in such mechanical highlights as an
all-aluminium crankcase with a lightweight crank assembly, forged pistons and
low-friction cylinder wall, not to mention an intercooler based upon that of
the SLS AMG supercar and the result is a powerplant eclipsing that of pretty
much every performance hatchback out there.
Performance is scintillating; the A45 AMG
accelerates to 100 km/h in just 4.6 seconds on the way to an electronically
limited 250 km/h top speed.
The
AMG Drive Unit could hardly be simpler to use
Lean And Clean
But, as AMG chairman Ola Källenius explains
in his interview, the balance of performance and efficiency is integral to AMG
cars. And the A45 is no exception. As a member of Mercedes-Benz’s Blue DIRECT
engine family, the A45 powerplant’s high-pressure, direct fuel-injection
system, combined with stop/ start technology and a number of thermal-management
measures pare the average fuel consumption down to just 6.9 litres/100 km,
while CO2 emissions, at 161 g/km, already comply with EU6 emissions legislation.
The
optional sat-nav system is respectable enough
Although it bristles with innovative
performance and efficiency features, the A45’s powerplant still adheres to
AMG’s one-man, one-engine philosophy, whereby each engine is meticulously
hand-built and bears the fitter's signature.
Four To The Floor
Channelling this power to the road is no
mean feat, and here two of the A45 AMG’s state-of-the- art drivetrain
technologies combine to fuse formidable performance with precision control.
