New hi-po four sounds death knell for BMW’s atmo six

IN CONTRAST to BMW’s apparent reluctance to turbocharge petrol engines for three decades after the demise of its legendary 2002 Turbo of the 1970s, it has thoroughly embraced the technology in recent years.

Now the company has developed a 2.0-litre four-cylinder turbocharged petrol engine that offers similar performance figures to – and is set to replace entry-level versions of – its iconic 3.0-litre, naturally aspirated straight-six.

The new power unit appears to have rendered non-turbo BMW sixes obsolete and the Bavarian manufacturer appears to acknowledge this in its nomenclature, retaining the xDrive28i identification on the X1 in which the new engine makes its world debut to replace the old 3.0-litre unit.

BMW Australia has confirmed that the new engine will find its way into locally delivered cars and will be introduced across the range, but no further details are available at present. In the meantime, the 3.0-litre engine lives on in the 5-Series, Z4 and X3, at least for the time being.

BMW Australia did not bring the X1 xDrive28i here, but introduced an xDrive25i flagship in October last year, fitted with a 160kw/280Nm version of the 3.0-litre straight-six. With the new four-cylinder likely to become available in various states of tune, expect a ‘low-blow’ version to also end up in the engine bay of BMWs with 25i badging.

The new engine is the first four-cylinder to feature the Munich marque’s ‘TwinPower’ technology, which combines twin-scroll turbocharging (which separates the exhaust gases from each pair of cylinders to reduce turbo lag) and direct fuel injection with variable camshaft timing and valve control to achieve higher peak power and torque output than would normally be expected for an engine of a given size.

The performance figures show the new turbo-four produces 180kW at 5000rpm and 350Nm from 1250rpm. By contrast, the 3.0-litre delivers 10kW more power, but at 6600rpm, and offers 40Nm less peak torque while requiring the driver to rev up to 2500rpm to access it.

Mated to a six-speed manual in the X1, the new engine accelerates from 0-100km/h in 6.1 seconds, beating the outgoing six-cylinder by 0.7s.

At the same time, fuel consumption is reduced by 16 per cent to 7.9L/100km, whether paired with the standard six-speed manual gearbox or an optional eight-speed automatic. CO2 emissions also reduce 16 per cent from 219g/km to 183g/km.

By dropping two cylinders, the X1 xDrive28i’s weight is reduced by 30kg and the new engine’s fuel efficiency benefits are supplemented by BMW’s standard EfficientDynamics kit including idle-stop, brake energy recuperation, shift light and on-demand ancillaries.

BMW has also announced that an M Sports package will become available across the X1 range, comprising the usual exterior and interior styling and suspension modifications.