The Audi RS3 rival is available to order now in two trim levels, with prices starting at £50,570 for the hatchback and £52,145 for the larger Coupé variant. Entry-level models come equipped with 19in five-spoke alloy wheels, red brake calipers, AMG suspension, a performance steering wheel, heated front seats and keyless entry as standard.
Range-topping Plus trim adds additional equipment as standard, including AMG's track-focused aero package, adaptive damping suspension, 19in forged alloy wheels, electrically adjustable front seats and a Burmester sound system.
The company is claiming class-leading power, performance and features for the second-generation A45 S 4Matic+ – a car it says will challenge the established mega-hatch order with up to 415bhp, a supercar-baiting 0-62mph time of 3.9sec and a new switchable Drift mode function.
The A45 heads a quartet of rapid new compact Mercedes-AMG models equipped with the M139-designated four-cylinder petrol engine.
The turbocharged 2.0-litre unit uses many of the technical solutions already developed for Mercedes-AMG’s twin-turbocharged 4.0-litre V8 petrol engine and it will be offered in two distinct power outputs. In the new standard A45 4Matic+ and CLA45 4Matic+, the M139 develops 387bhp at 6500rpm and 354lb ft of torque between 4750rpm and 5000rpm. That’s 85bhp and 59lb ft more than the A35 and CLA35.
In its highest state of tune, with 2.1 bar of turbocharger boost pressure and water injection for its twin-scroll turbocharger, the M139 provides the A45 S 4Matic+ and CLA45 S 4Matic+ with a class-leading 415bhp at 6750rpm and 369lb ft between 5000rpm and 5250rpm.
This marks the new AMG motor out as the world’s most powerful four-cylinder series-production engine. It also represents an increase of 39bhp and 18lb ft on the outgoing M133 engine of the previous A45.
Despite giving away 28bhp and 15lb ft to the A45 S 4Matic+, the standard A45 4Matic is claimed to be just 0.1sec slower to 62mph, at 4.0sec, and its top speed is limited to 155mph.
Both new A45 4Matic+ models have the same combined cycle fuel consumption and CO2 emissions, at 34.0mpg and 189g/km. The new AMG engine comes mated to a standard eight-speed dual-clutch gearbox and a newly developed multi-plate clutch 4Matic+ four-wheel drive system. This features an AMG torque control function that separates electronically controlled clutches within the rear axle to vary the amount of drive sent to each individual rear wheel.