In the quest to further reduce car emissions the WLTP also known as, Worldwide Harmonised Light Vehicle Test Procedure introduced a new exhaust particulate filter for petrol-powered vehicles sold in Europe after September 2018. What does this mean for car enthusiasts? Well, a simple drag race between two virtually identical Audi RS3’s should give us an answer. 

Before we get into the drag race results, what is a GPF exhaust filter? In Europe, all diesel-powered vehicles come with an exhaust particulate filter to reduce soot emissions. A similar filter was recently introduced on petrol-powered vehicles for the European market called a GPF. This new filter will reduce emissions but will it negatively affect a car’s performance? 

Gallery: Audi RS3 drag races its predecessor: Are eco norms ruining the fun?

To test the new WLTP mandated GPF's effects on performance, the team from Carwow decided to race two RS3s. One RS3 Hatchback hails from a time before the mandated exhaust GPF while the other has a fresh regulation friendly GPF. So does an emissions friendly exhaust make your car slower?

Based on the race results, it’s complicated. The pre-GPF RS3 seems faster off the line while the GPF RS3 has a faster mid-range. At higher speeds above 150 mph, the pre-GPF RS3 blows away the new car at a surprising pace. With razor-thin margins like this, the team had to move on to a more scientific test on a dyno.

On the dyno, both RS3s produced 355 bhp at the wheels during their dyno runs which work out to about 405 bhp at the crank. The dyno graph shapes tell a very different story. The pre-GPF RS3 produces its peak torque 500 rpm sooner in the rev range when compared to the new GPF installed RS3. When it comes to the top end of the rev range the pre-GPF RS3’s torque curve slowly dies down while the GPF installed RS3 sees a sharper decline in torque.

Although horsepower numbers may look the same on paper, the GPF certainly has an effect on the power delivery of our favourite performance cars. As time goes on, automakers will certainly find a way to make similar power with the new exhaust GPF.