PPFs

By Rohan Santhosh

On the 1st of September, 2017, the EU passed the Euro 6 emission limits. This meant that new cars were supposed to reduce the amount of CO2 , Nitrogen Oxides and particulate matter that they were emitting. This is a good thing in the sense that pollution is reduced, but the downside of these emission laws was that all new cars needed to be fitted with a PPF(Petrol Particulate Filter). This filter reduces the emissions of all new cars but unfortunately reduces the amount of sound that a car makes. The council did away with the old NEDC(New European Driving Cycle) tests and introduced the new WLTP(Worldwide harmonized Light-duty vehicles Test Procedure) test  for emissions. The  WLTP test is a much more accurate representation of the emissions, economy and noise of cars. 

As per the Euro 6 norms, sports cars must be tested in their loudest exhaust setting. This means that the sound made by cars in their loudest mode is reduced to a much quieter level. This might be beneficial to the general public but it reduces the fun of driving a fast, loud car into just driving a fast car. Most sports car brands that one would expect a loud and fast car from are now being forced into following the norms. This means that future cars on the road, while eco-friendly, would be a lot less fun. Some brands have escaped fitting the PPF to their cars for the past two years but as time passes, the council’s axe is bound to land on each and every car manufacturer. 

Cars are not usually engineered to make a loud noise, but the loud exhaust note is generally a by-product of trying to ensure a free-flowing exhaust to make as much power as possible.

To replace the lost enjoyment, manufacturers have to focus on meticulously creating the exhaust in such a way that despite having to fit the PPF to their cars, their cars sound good. Jaguar, with its new F-type which is fitted with a PPF, have managed to make it sound exceptional. Ferrari, on the

Roma have decided to remove the rear silencer to compensate for the noise lost due to the PPF. Other manufacturers have decided to play engine noises through the speakers or also pump in extra intake noise to the cabin to make the driving experience more engaging. It is also illegal to fit an exhaust system to the car that increases the loudness of a car, which means that cars cannot exceed the threshold of 74 decibels. 

Obviously, PPFs are a good thing all-round.

Despite their unfortunate drawback of making cars more boring, I think that the Euro council has made a good decision to fit them to cars to curb the effects of global warming. As more electric and hybrid cars are being introduced, this can be seen as the slow but clear transition from the more conventionally exciting ICE cars to electric power.