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Sep 25, 2023

GTS Oh, Yes: 2016 BMW M4 GTS Technical Deep Dive

Representing the bleeding edge of modern BMW performance, the 2016 M4 GTS

Representing the bleeding edge of modern BMW performance, the 2016 M4 GTS resides on the fine line between street car and dedicated track car. At $134,200, it is the most expensive M car, and for good reason. Only 750 of these heavily modified M4s will be produced, with 300 dog-eared for the U.S. (Sorry, Canada, you only get 50.) The only option given to the lucky few who sign on the dotted line is the exterior color: Alpine White, Black Sapphire, Mineral Grey, or Frozen Dark Grey metallic, otherwise known as matte gray. We suspect nearly every GTS will roll out of the assembly plant wearing the frosty coating. Then again, if you go with white, you may have a rare bird. We’ve dug deep into the car to deliver its secrets—and the details are shocking. Flip through to learn about them for yourself:

Inside, there are few comforts. Microsuede trims many interior surfaces, including the dash. Note the lack of a center-console bin. Beneath the dash is a carbon-fiber support tube to further reduce mass. Unfortunately, all the weight savings are offset by components added to make the GTS into the hellbeast it is. This car weighs 3538 pounds, or just 43 pounds lighter than the 2014 M4 we lapped at VIR two years ago.

The steering wheel is more or less the same as stock M4s but wrapped in microsuede and featuring red and blue contrast stitching.

The M4's optional seven-speed dual-clutch automatic is standard kit here. Like the M3/M4, the GTS has selectable modes for engine response and steering, but there is no cockpit-located adjustability for the dampers. If you want to tune the compression and rebound, you have to get out of the car and turn some dials. (More on that later.) The GTS is loud, and putting the engine setting in Sport or Sport+ opens butterfly valves in the exhaust. There are no artificial engine sounds here—just pure inline-six battle cry.

These one-piece buckets are standard in the European cars. U.S. cars will get a lightweight version of the seats that come with the new Competition package–equipped M3/M4s. At the same time, while Europeans have to pay extra to get the orange roll cage, all U.S. cars will come with it. It's up to you to find a set of harnesses if the standard seatbelts aren't secure enough for you.

A better look at the standard rollover protection—but it's not like you can miss it when it's that color, can you? The fire extinguisher, cage, and six-point harnesses are part of a package in Europe. The shelf beneath the cage is made of fiberglass-reinforced plastic.

The window switches and door latches are the only interior-door components that carry over from the regular M4. The inner-door trim is a lightweight material that's also found in the i3. It is basically made from recycled trimmings that would otherwise be swept into a dumpster. And while the door pull looks like it's cribbed from a 987 Porsche Boxster Spyder, it is actually just a pull and does not unlatch the door. Without it, a fully harnessed driver couldn't close the door at its widest opening.

The underside of the GTS's hood shows off its carbon-fiber weave. The roof and trunk also are made of carbon-fiber-reinforced plastic, but those components are CF in the base car, too. It is shockingly light and easy to lift.

BMW changed only two physical things for its S55 inline-six for the GTS, and neither can be seen by looking at the engine. The first is adding the water-injection system that helps the GTS put out 493 horsepower and 443 lb-ft (up from 425 hp and 410 lb-ft in the base M4).

The second thing that changed in the S55 is a slightly longer oil-level sensor in the sump. It is needed because the GTS's engine uses an extra liter of engine oil to prevent starvation during high-g maneuvering.

The orange splitter, yet another carbon-fiber component, can be manually extended 2.4 inches for maximum downforce.

Extending the lip delivers as much as 63 pounds of downforce on the front axle at 186 mph.

Balancing the front axle's downforce is this three-position rear wing. In the most aggressive position (shown here), the wing makes 210 pounds of downforce at 186 mph. If you guessed that it was made of carbon fiber, you’d be right.

Crisp, refreshing water. This is the 1.3-gallon water tank for the water-injection system. It is located under the trunk floor where you’d normally find the tire-mobility kit. The system injects water into the intake plenum at 145 psi, creating a fine mist that is almost instantly turned into vapor. The energy (heat) that turns liquid to gas cools the intake temperature even more than an air-to-liquid intercooler can. The result is an increase in boost pressure from 17.2 psi in the M4 to 21.6 in the GTS.

Next to the tank is the water-injection valve body and pump. It controls the flow to and from the injectors, which are cribbed from a diesel's urea-injection system. Every time the car is shut down, the pump drains all the water in the stainless-steel line to prevent corrosion. This also reduces the chances of ice in the system in colder climates. BMW says the system works in ambient conditions above 41 degrees. If you run the car without water, the engine reverts to the Competition package tuning with maximum output of 444 horsepower.

A small tool kit comes with every GTS. The spanners are to adjust the ride height by way of threaded spring perches. BMW ran the car in the street height when setting the 7:28 lap of the Nürburgring to avoid bottoming out over curbs, but lowering the car—0.8 inch is the maximum amount of drop—will improve the effectiveness of the splitter. The orange star-looking thing is for adjusting the front-axle rebound damping.

The $8150 carbon-ceramic brakes, optional on regular M3/M4s, are standard on the GTS. The only change engineers made to the six-piston front and four-piston rear brakes, aside from retuning the ABS and stability control to compensate for the higher grip of BMW-spec Michelin Pilot Sport Cup 2 tires, was fitting a slightly more aggressive rear brake pad, again to take advantage of available grip.

You need to remove a wheel to get a good look at the three-way adjustable coil-over dampers of the front axle. You can just barely see the orange dial of the high-speed compression adjustment (14 positions) on the bottom of the external reservoir. The six-position low-speed compression adjustment is just below that, blocked by the front-rotor shroud. To adjust rebound, you have to remove some foam caps from the top of the strut mount and use the rebound tool to dial in one of 16 positions.

K.C. Colwell is Car and Driver's executive editor, who covers new cars and technology with a keen eye for automotive nonsense and with what he considers to be great car sense, which is a humblebrag. On his first day at C/D in 2004, he was given the keys to a Porsche 911 by someone who didn't even know if he had a driver's license. He also is one of the drivers who set fast laps at C/D's annual Lightning Lap track test.

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