Prepare to Yield: 2018 BMW M4 GT4
Launched in May of 2017, the BMW M4 GT4 is quickly gaining traction as a formidable racing platform. After earning its scars in some of the most arduous competitive environments at Duabi and Nürburgring the car has already proven it's more than capable of handling 24 hours of full tilt driving. And today, BMW is hoping to continue its success in North America by making its sales debut at Watkins Glen during Sahlen's Six Hours of the Glen endurance weekend. It's taken on some of the toughest races already so for the M4 GT4 it should be a walk in the park.
Compared to the base M4 and M4 GTS there is a world of difference. For one thing, the M4 GT4 is not road legal. It's dedicated only to the sport of racing so it has none of the frivolities or comforts of a luxury coupe. What it does include are motorsport specific parts to improve downforce, add lightness, adjustability, and reduce maintenance time.
The most visible part of the GT4 package is its aerodynamics. Equipped with front dive planes, front splitter, and an adjustable rear wing all made from carbon fiber reinforced plastic, the M4 GT4 takes on a more serious and business like visage. Its roof, doors, battery cover, and front bonnet are also transformed into CFRP for a lower center of gravity.
Its wheelbase, length and width, barring the front splitter, is the same as the M4 but its height is one inch lower depending on the suspension setup. Racing regulations and track adjustments ultimately determine how close to the ground the M4 GT4 sits but its stabilizers, Ohlins dampers, and springs are adjustable at all four corners. A new spring dome design allows teams to change the front wheel camber to improve tire grip under load. And a spherical metal bearing replaces rubber bushings usually found in street cars. Spherical bearings are more durable and stiffer than rubber or polyurethane bushings but comes at a cost in ride harshness and well... cost.
Brakes consist of 390mm and 355mm ventilated and slotted discs. The discs are designed to stay cooler in long term racing situations so it's helped by a two-suction brake cooling system. AP Racing 6-piston and 4-piston fixed calipers squeeze endurance spec braking pads also designed to last longer than usual. Drivers can adjust brake bias with a dial on the inside changing the position of a balance bar. This balance bar pre-loads the master brake cylinders to adjust the pressure sent to each caliper. Sitting on the same hub as the brakes is a 5-stud mount holding 11 x 18 alloy wheels. Teams can supply their own tires but the M4 GT4 comes with a set of 300/660 (Equivalent to 335/30) R18 Hankook F200 racing slicks. Be advised, those racing tires are $510 each.
Sitting under the bonnet is BMW's recognizable S55B30T0 3.0-liter turbo straight-six. Its output of 425 hp and est. 415 lb-ft of torque is higher than the base M4 but lower than the M4 GTS as it lacks the trick water sprayed intercooler system in the back. Instead, a 33 gallon (125 liter) FT3 fuel cell takes up all the boot space - double the capacity of the road car. The tank is designed to withstand fires and impacts while allowing quick refueling from both sides of the M4 GT4. Both the horsepower and maximum fuel level are subject to regulatory limitations but BMW has made it easy to adjust its output with pre-approved presets in the form of optional power sticks.
Final mechanical touches involve its 7-speed dual clutch transmission and dynamic stability control system undergoing the BMW Motorsport treatment. Past the transmission, BMW upgraded the driveshaft with a carbon model and deployed a Drexler mechanical locking differential in the rear. Additionally, the engine mount, output shaft, and wheel bearings have all been adjusted for motorsport use. If the team needs to get fix something on the underside in a jiffy the integrated air jacks round out its true motorsport characteristics.
Drivers on the inside sit in a BMW Motorsport full bucket halo seat with 6-point Schroth Endurance safety harness. Surrounding the seat is an FIA spec welded roll cage, safety net, and optional race taxi seat. The seat and the pedal box are both the same models as the ones from the M6 GT3. It may appear barren, but the M4 GT4 is loaded with technologies that help the team and the driver. For basic needs, the car is equipped with air conditioning, telescopic steering column, parts for a driver hydration system, power mirrors, and a Makrolon polycarbonate heated windshield to prevent fogging. For more technical readouts BMW set the M4 GT4 with a lightweight wiring harness so engineers can connect and read its telemetry right off the bat.
Although the M4 GT4 is not as fast as the M6 GT3 flagship, BMW and their racing heritage has proven numerous times their motorsport cars are savage competitors on the track. Out of the 20 top positions in the 2017 24 hours of Nürburgring 7 of them were BMWs, and the M4 GT4 in 36th overall was first place in its class. Given a few more years we can expect to see more cars in the GT4 class as the M4 GT4 is half the price of the M6 GT3 at $196,000. It's clear a car like this in the right hands is a force to be reckoned with. Porsche, Mercedes, and Audi now have a gulf to fill. But until then, they should stick to the right and let this M4 GT4 pass.