That’s right: in terms of power per litre of displacement, the CLA45 (and forthcoming, same-engined A45 hyper hatch) will produce around 310kW from a highly boosted 2.0-litre turbo four, making them the undisputed world leaders with 155kW/litre, and nudging aside the current specific-output champion, the 149kW-per-litre McLaren Senna.
We don’t know exactly how Mercedes-AMG has reengineered the A35’s 225kW/400Nm engine to achieve the mega outputs, but boss of the division, Tobias Moers, is on record as stating there are limited shared components, and the 45 engine features its own specific crankcase and cylinder head.
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The next-gen CLA45 is set to adopt a new eight-speed dual-clutch transmission (replacing the seven-speed used in the A35) together with a faster-reacting all-wheel-drive system that offers greater variability in the drive split between the front and rear wheels, plus a torque vectoring function across the rears for added on-the-limit handling balance.
Moers has said the all-wheel-drive system that will underpin the CLA45 “doesn't know what understeer means”, and Mercedes-AMG has already made it abundantly clear that the CLA45’s mechanical sibling, the forthcoming A45 hatch, has a drift mode. This was put into starkly sideways relief in an official AMG video released late last year titled “Not Another Christmas video” showing an A45 prototype laying huge drifts around a test track in northern Germany.
In terms of external changes that will instantly identify the CLA45 over the CLA45, well, we have a pretty clear idea of that thanks to what appears to be an internal balls-up on Mercedes’ own website. On the German configurator for the recently revealed CLA35, there's an option for the AMG Night package, showing a yellow CLA35. But when you click to get more information on the package, there's a second photo provided that shows the (officially unrevealed) CLA45 S. The gunmetal grey car is clearly badged as a CLA45, and the rear view shows four large exhaust outlets (the CLA35 has only two) nestled in an aggressive rear diffuser. There are also larger red front brake calipers visible, clamping what appear to be larger diameter brake discs.
Expect the CLA45’s official reveal to come in the third quarter of this year, with Australian sales not due until well into 2020.