Porsche to go almost all turbo

Porsche's most fearsome flagships have long been turbocharged (think 911 Turbo and GT2), as have many of its most affordable SUVs (thanks to Volkswagen-sourced V6 turbo-diesels), but within a few years almost all of the German sports car brand's model range will be force-fed.

Driven wholly by Europe's 95g/km fleet-average CO2 emissions mandate from 2020, Porsche's gradual move to downsized turbocharged engines in the search for efficiency began with the all-turbo Macan range and stepped up with its larger SUV sibling, the Cayenne.

The facelifted Cayenne S and GTS both swapped their 4.8-litre naturally aspirated V8s for smaller and cleaner – yet more powerful — 3.6-litre twin-turbo V6s, leaving only the base petrol model and the (supercharged) Cayenne S E-Hybrid plug-in without a turbo.

The second-generation Panamera is expected to follow suit, as are the facelifted Boxster and Cayman, which in 2016 will debut Porsche's first four-cylinder engines since the 968 disappeared decades earlier, in 1995.

Of course, all members of Porsche's new modular flat-four engine family – from the entry-level 2.0-litre to the 2.5-litre for Boxster/Cayman S models – will be turbocharged, as well as being more powerful and efficient than the 2.7- and 3.4-litre flat atmo sixes they replace, with up to 295kW.

However, turbo-four power will not feature in the facelifted 911, which will debut before the boxer-four twins at the 2015 Frankfurt motor show next October (four years after the current 991-series debuted there in 2011), before being rolled out here in early 2016 – four years after it went on sale here in February 2012.

As these fresh spy shots of the revised 2015 Targa and Turbo Cabriolet show, the 911 midlife makeover will bring only subtle cosmetic changes, limited to reshaped front air intakes and LED daytime running lights, and larger tail-lights.

More significant changes occur under their rear engine covers, where turbocharged versions of the current Boxster/Cayman's smaller flat sixes are expected to appear.

Our sources say the entry-level Carrera will revive the 2.7-litre capacity employed by 911s in the 1970s and '80s with a turbocharged version of the flat six from the current entry-level Boxster /Cayman for the base 911, lifting its output from 257kW to about 300kW.

Meantime, the Carrera S will downsize from an atmo 3.8 to a turbo 3.4, hiking its peak power from 294kW to 395kW – more than the current 911 Turbo's 383kW base figure.

Turbo, Turbo S and GT2 versions of the 911 will keep their big-bore turbo sixes to produce more than the 412kW of the existing Turbo S kingpin, leaving just the purest, most track-focussed GTS and GT3 RS variants – and perhaps the 911 Carrera S E-Hybrid plug-in – as the only exceptions to the new all-turbo 911 rule.

That will make next year's new GT3 RS and the new 911 GT3, which launches in Australia this week with a 331kW 3.8-litre atmo flat six that revs to 8500rpm, the last non-turbo versions of the 991-series 911 to be launched before the next all-new 911 later this decade.

Sticking to normal aspiration for the GT3 not only maintains the free-spinning nature of Porsche's customer race car, but keeps costs down for the one-make Carrera Cup series for which the GT3 road car is designed.

If they are approved for production (and that's a big if, given the Volkswagen Group's current freeze on the development of additional models), Porsche's next two all-new models – the sub-Panamera 'Pajun' mid-size sedan and sub-Boxster '718' compact coupe – are likely to continue the Zuffenhausen car-maker's headlong drive towards forced induction.

There's no doubt all of Porsche's upcoming smaller-displacement turbo engines will bring more performance, lower consumption and emissions and a wider spread of torque than the boxers they replace, but it remains to be seen whether they deliver the sound, response and rev range its iconic flat sixes are famous for.