THE PROBLEMWITH PAR­TIC­U­LATES

911 Porsche World - - News And Views -

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.

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