Video: 2018 BMW M4 CS vs 2018 Porsche 911 GTS At Nürburgring and Austria
It could be argued these two German sports cars aren't really comparable. The Porsche is purpose built from the ground up to be a performance machine. BMW extensively modifies and tweaks their 3 Series to compete. Porsche hangs the engine over the rear axle. BMW settles their engine in the front. Porsche uses six horizontally opposed cylinders. BMW uses six cylinders in a straight line. Porsches, especially the GTS, are more expensive in multiple countries compared to the BMW M4 CS.
But budget and logistical convenience dictate how Motor Trend runs a Head 2 Head segment. In this case, they have to fly a camera crew, production crew, and two presenters to Germany in addition to finding two cars with similar performance with booked time for the road and track many months before it can be executed.
At least on paper, these two cars are close enough. The 2018 Porsche 911 GTS uses a turbocharged 3.0-liter flat-six to produce 444 horsepower and 405 lb-ft of torque. It can be specced out with a 6-speed manual or 6-speed PDK allowing it to jump from zero-to-60 mph in 3.5 seconds. Its PDK is oft considered the best dual-clutch example currently sold today. The BMW M4 CS offers the same displacement from its twin-turbo S55 straight-six, but more power is on tap at 453 horsepower and 442 lb-ft of torque. The hopped up M4 CS is heavier than the 911 GTS so its zero-to-60 mph is only 3.7 seconds at best. It can only be optioned with a 7-speed M dual-clutch unit though it's not as sophisticated as Porsche's offering.
To see how it runs in the real world, check out the 25-minute long episode of Head 2 Head with Jethro Bovingdon and Jonny Lieberman.