New York show: BMW Z4 to get TwinPower four-pot

TEUTONIC turbo-meisters BMW have used this week’s New York International Auto Show to announce that the high-output four-cylinder 2.0-litre ‘TwinPower’ turbocharged petrol engine that debuted in its X1 crossover will make it under the long bonnet of the Z4 roadster by the end of this year.

Like the X1, the Z4 will receive 28i nomenclature for variants fitted with the new engine. While the X1’s engine is rated at 180kW, BMW quotes 176kW for the Z4 – although it points out that final output and performance figures won’t be finalised until mid-year.

As GoAuto reported when the X1 received the engine in January, the new powerplant’s power output comes close to that of BMW’s naturally-aspirated straight-six in 28i/30i specification while producing an extra 50Nm of torque.

BMW employs twin-scroll turbocharging (which separates the exhaust gases from each pair of cylinders to reduce turbo lag), direct fuel injection, variable camshaft timing and valve control to achieve power and torque outputs higher than would normally be expected for an engine of this size.

The power and torque delivery characteristics of the turbo four also promise to make it a more usable unit, peak power coming in at 5000rpm rather than 6,600 and maximum torque from just 1250rpm as opposed to 2600rpm.

As would be expected, the smaller capacity and lower cylinder count also contribute to significant fuel and CO2 savings of 16 per cent over the six-cylinder it replaces in the X1. According to overseas reports, the engine is responsive, refined and efficient but lacks the soundtrack and character of BMW’s iconic straight-six.

In the manual X1, the turbo four enables acceleration from 0-100km/h in 6.1 seconds, beating the outgoing six-cylinder by 0.7s, so with less weight to haul around, the Z4 with this engine could achieve the sprint in five seconds or less (the manual Z4 sDrive30i reaches 100km/h in 5.8 seconds).

The X1 and Z4 with the new engine remain unconfirmed for Australia. All BMW Australia can reveal at present is that the engine will be coming here towards the end of this year “across a number of models in the range”.

Should the engine be introduced into locally-delivered Z4s, the promise of extra performance coupled with lower fuel consumption and emissions could inject some life back into Australian Z4 sales, which are down 66.1 per cent for the first quarter of this year with just 37 registrations compared with 109 for the same period in 2010.

The current folding hard-top Z4 has averaged 25 units per month since its May 2009 launch. Its high point was 50 sales in June 2010, with a low point of just nine sales in October of the same year. BMW’s overall first-quarter sales this year total 3927, down nine per cent.