A45, CLA45 Exposed! 310kW/500Nm Mercedes-AMG redefines the hot hatch
Mercedes-AMG is set to once again rewrite the hot-hatch rulebook, revealing the all-new A45 and its four-door twin, the CLA45, at the Goodwood Festival of Speed. The original A45 redefined what a hot hatch could be in terms of power, speed, cornering ability and price, but AMG has left no stone unturned in developing its successor to an even higher level, promising supercar-scaring speed, greater comfort and Drift Mode.
It seems sensible to start at the engine, given the new 45s’ 1991cc M139 turbo four-pot spits out an incredible 156kW/litre. Overseas markets will offer base versions with 285kW/480Nm, but M-B Australia has confirmed it will only take the higher-spec ‘S’ models producing 310kW/500Nm, capable of sprinting to 100km/h in just 3.9sec in A45 guise, the CLA adding 0.1sec to that. Top speed is limited to 270km/h.
To extract these remarkable numbers from such unremarkable capacity, AMG literally performed a 180 on the M260 found in the A35, flipping the engine so that the turbo and exhaust manifold nestle against the firewall and the intake sits up front. This not only improves aero by keeping the nose lower, but also shortens the intake paths to spool the turbo up quicker.
The turbo itself is a twin-scroll design with roller bearings on the compressor and turbine wheels – tech nicked from the GT63 S – to reduce friction, and it spins to 169,000rpm. It delivers a massive 2.1bar (30.2psi) of boost, which would blow a regular engine apart.
The all-aluminium closed-deck crankcase contains a forged steel crankshaft, the pistons are forged aluminium, the cylinders are coated in an iron-carbon alloy using Merc’s patented Nanoslide technology, and a baffled sump ensures adequate lubrication during high-g loadings.
This new engine revs much harder than the previous A45’s, which produced its peak of 280kW at 6000rpm and maximum torque from 2250-5000rpm, with a 6250rpm redline. That redline now shifts to 7000rpm, the new 45s producing 310kW at 6750rpm and 500Nm at a high 5000-5250rpm. Such peaks suggest massive turbo lag, but AMG claims the torque curve has been carefully ‘shaped’ to deliver the progressiveness of an atmo engine.
A new eight-speed dual-clutch gearbox debuts, but of more interest is a departure from the traditional Haldex-style all-wheel drive of their predecessors, the front-biased layout majoring on traction and stability but unable to deliver ultimate driving thrills.
The latest 4MATIC+ system incorporates a pair of electromechanically controlled multi-plate discs in the rear diff to allow independent control of the torque being sent to each side. Overpower the outside rear wheel and, ‘Hey presto!’ Drift Mode!
There are six drive modes – Slippery, Comfort, Sport, Sport Plus, Race and the customisable Individual – which alter the powertrain response, steering weight, stiffness of the three-mode adaptive dampers and characteristics of the 4MATIC system. This has a further four settings – Basic (stable), Advanced (neutral), Pro (more neutral) and Master (slight oversteer).
Suspension is MacPherson strut front and four-link rear, and the S models use larger 360mm front discs and six-piston calipers supported by 330mm discs and single-piston calipers at the rear.
Identifying an A45 should be easy thanks to the 12 vertical louvres in the grille, wider front guards and gaping 90mm exhaust tips.
Inside is an Alcantara-wrapped AMG Performance wheel, racy Performance seats and flash twin instrument/infotainment screens controlled by Merc’s latest MBUX system. Expect a Q1 2020 local arrival, with pricing to be confirmed closer to that time.
RIGHT Yellow interior highlights another signature of the ‘S’ models; digital instrument screen has AMG-specific displays.
ABOVE RIGHT All-new M139 sets new benchmarks for four-cylinder performance.
RIGHT Australia will receive higher-spec S models with larger brakes and red calipers.