THE PROBLEMWITH PARTICULATES
What, exactly, is going on with Porsches and petrol particulate filters? The short answer is that we don’t know. Porsche put out a statement indicating that the 911 Carrera GTS 4 will soon be fitted with the filter, as will some 718models. Beyond that, we know nothing certain. Will the filter impact power? Will it put pay to models like the GT3, GT3 RS, GT4 and even the upcoming 911 Speedster in Europe? It’s all amystery.
What we do know is that the entirematter of petrol particulate filters is a bit of a farce. Indeed, it’s just the latest in a line of unintended consequences resulting from the quest for lower carbon emissions fromcars. One of the biggest downsides to that pursuit has been awful air quality in European cities. The widespread adoption of diesel engines has probably had limited impact on overall world carbon emissions. But it has influenced local urban air quality dramatically andmuch for the worse. Measures of urban air quality since the increase in diesel car sales have shown a significant decline. So it was hardly a surprise to find the Vwgroup had been cheating emissions tests. Anecdotally, that observation that diesel cars often emit unpleasant smoke is obvious enough.
Unfortunately, the quest for lower carbon emissions has alsomade local emissions frompetrol cars worse, too. Particulate emissions frompetrol engines have only become a problemsince the introduction of direct injection engines. Older indirect injection engines aided by a catalytic converter emit extremely low levels of particulates. Once again, then, lower carbon emissions have come at the cost of local air quality.
Theymay also come at the cost of some fantastic Porsche sports cars if it turns out that applying a filter to the likes of the 911 GT3 reduces engine power and perhaps the soundtrack, too. It’s ironic to think that driving something like a 997 GT3 through a city centre is better for local air quality than the fleets of supposedly low-carbon diesel hatchbacks that largely fill the streets. Happily, the tide has now turned against diesel and European urban air quality should once again improve. In themeantime, there’s an important lesson of unintended consequences in oversimplifying the complicated question of cars’ emissions down to a singlemetric of CO2 levels. Let’s hope future regulations are far, farmore enlightened.