The SL43 represents as the biggest assignment yet for Mercedes-AMG’s famous hot hatch engine.

WILL the fanbase still cry ‘phwoar’ when, in an engine bay that has in the past been home to V8s and V12s, now resides a ‘four’?

Mercedes is clearly up for taking that risk. Announcement comes today of the Mercedes-AMG SL43, a sister ship to two V8-powered editions announced late last year but powered by half as many cylinders.

From the gist of information shared for this part of the world, the new entry level derivative will be coming to New Zealand toward the end of this year.

The powertrain is new to SL, but has plenty of AMG cred, being the much-admired turbocharged 2.0-litre engine that goes into the A45 S, the hottest version of its smallest car, the A-Class.

It’s no Starfire experiment. Yes, the car is large, but the engine has rated for some years now as the most powerful of its kind and, in this implementation, it picks up a world-first production car usage of an electric exhaust gas turbocharger. That’s a tech Benz says it has directly plucked from the Mercedes-AMG Petronas F1 car.

Rotated to sit longitudinally and drive the rear wheels – and matched with a nine-speed multi-clutch automatic transmission – the 'M139' four-cylinder engine quotes outputs of 280kW and 480Nm.

The electric turbo installation sandwiches an electric motor between the two wheels of the turbocharger, allowing it to spin the turbo up when there's not enough throttle to do it with exhaust gases alone.

It’s fed by a 48-volt mild-hybrid system, incorporating a belt-driven starter generator unit capable of providing a 10kW electrified boost under hard acceleration, speed up the start-stop system, or switch off the engine under low load, allowing the car to 'glide'.

Mercedes-AMG claims a top speed of 275kmh and a 0-100kmh time of 4.9 seconds.

That’s just eight tenths down on the time claimed for the all-wheel-drive SL55, which runs a 350kW biturbo V8. That 4.0-litre engine also goes into the SL63, where it creates 430kW.

This isn’t the first four-cylinder version of a large Mercedes two-plus-two roadster but it has been a long time since the last – 60 years, in fact.

Reinstating a four-cylinder is all about efficiency; lower emissions and better economy. In the combined WLTP cycle, the SL43 returns between 9.4 and 8.9 litres per 100km. The same engine might well next end up in the new AMG C63. Benz has already confirmed that car has lost its V8 completely.

Elsewhere, the base version comes fitted as standard with steel suspension and an AMG Dynamic Select system with five driving modes, or six if you opt for the AMG Dynamic Plus package that adds ‘race’ to the existing ‘slippery’, ‘comfort’, ‘sport’, ‘sport plus’ and ‘individual’. The optional Plus Package also throws in a few more goodies to the mix, including a 10mm lowered suspension, different engine mounts, an electronically controlled limited-slip rear differential and yellow brake calipers.

How can you tell it’s the smallest-engined type? Not by the pipe count – there are four of those – but the exhaust shape; the pipes are round rather than angular. The SL 43 also runs on smaller 19-inch wheels as standard, but you can also get the larger 20 or 21 inch rims available in the eight-cylinder models as an option.

Also on the cost-extra list are an active rear-axle steering system that turns the rear wheels either in the opposite direction (up to 100kmh) or in the same direction (faster than 100 kmh) as the front wheels and all sorts of packages like the exterior carbon and high-gloss chrome kits.