The BMW Z4: it’s a car you don’t often see in tuning-circles, and rarer still in hardtop form. As a sportscar, it might be the Bavarian automaker’s truest offering: the long front end, short cockpit and almost non-existent tail section lends itself perfectly for great balance and optimal racing characteristics. Think Shelby Daytona Coupe or Datsun 240Z. Its capabilities urged the brass at BMW USA to enlist a GTLM version for the 2013 American Le Mans Series campaign and again as part of the newly-formed Tudor United SportsCar Championship for 2014, where it sits consistently at the top of the timing sheets. Compared to the Z4 M built by Slek Designs, the Team RLL Z4 GTLM is likely the only Z4 on the continent with as much carbon fiber. Even then, it probably still falls short.
The work done to the exterior of the car is immediately obvious. On close inspection, the carbon fiber is ridiculously tight-woven, with each seam butted perfectly to one another. We’re talking Beyoncé flawless. As far as carbon fiber builds go, the attention to detail is second to none, and even more impressive considering that it’s built by a couple of full-time college students.
The Z4 M made waves at SEMA 2013 as one of the most creative builds on the floor. Typically, projects like this requires vast resources that only a million-dollar operation can offer, but Alberto and Eulises Torres, cousins and co-owners of Slek Designs, simply know how to put their talents to work.
Like many of us, their foray into building began as with model cars when they were still just kids. From there it was on to Japanese vehicles before starting on string of Bimmers. Prior to the Z4 M, Slek Designs dove into the 1M, a stunning white widebody E92 M3, and an F10 M5. The 1M gave them their first taste of worldwide recognition, while the M3 opened a ton of doors as part of the SEMA 2012 lineup that also included sponsorships from Savini Wheels, Autowerks Suspension and Nitto Tires, all of whom have supported Slek throughout the company's existence.
When it came to Slek's next project, the Z4 was the perfect specimen. Along with being a different platform than most builders choose, each body panel on the car can be easily unbolted and removed. And with a composite manufacturer and designer at their fingertips, the sky was the limit. The only thing working against them was the six-month timeline leading into SEMA.
To make the deadline, Alberto and Eulises doubled their staff and focused all of their efforts on designing, molding and meticulously manufacturing each panel – 13 in all. At the same time they were organizing sponsors, parts and building the car in time for the show...while attending school. And you thought you were busy.
The simplicity of the design is what really separates this build from the rest. From afar, the bare carbon works perfectly with the classic gold RSV Forge 19-inch wheels and color-matched sticker work. There’s nothing overbearing or in your face, but as you get closer, the Slek body work enhances the BMW’s beautiful silhouette in every way.
The carbon process which created this piece of art is rare in the world of aftermarket constructors, but Slek Designs can basically build or replicate any part of your car in carbon fiber. The fitment on the Z4 is perfect, thanks to durable materials made using a special carbon honeycomb matrix and vacuum assisted resin transfer molding process (VARTM) akin to what is used in aerospace and Formula One applications. Put bluntly, it's top quality, built to last and the final result speaks for itself.
The front bumper and splitter suck in plenty of air and provide just the right amount of downforce; on the hood are twin cooling outlets reminiscent of the Z4 GTLM race car; behind the front wheels are giant vents that improve airflow through the body and down the side of the car into a set of rear intakes, which can be routed to help cool the rear stoppers. At the tail end, Slek’s intricate design utilizes four air outlets in the rear quarter panels and bumper to allow air to escape while connecting the widebody work with the main structure. The custom trunk and built-in duckbill spoiler completes a package that makes it look like a Dinan on steroids. In the end, weight savings on the body work total an incredible 300 lbs.
That reduction is felt throughout the car; in its handling, cornering and, most importantly, its power output. The S54 engine and VF Engineering supercharger kit push 570 horsepower, but the response is greatly increased thanks to a lightened load. The VF is also the fastest supercharger kit available for the Z4, making this a scary opponent in any situation.
The RSV Forged wheels? They were built to be show ready and track capable with help from monstrous Nitto Invo tires (275 mm front and 345 mm rear) and Ksport Kontrol Pro coilovers, which offer 36 levels of adjustable damping and are designed specifically for road racing.
Inside, things are kept simple. This is a BMW after all. But again, Alberto and Eulises decided that if the car ever has to prove itself on the track, Status Racing FIA-approved carbon seats, five-point harnesses and a gold SAE Motorsports custom roll cage will continue the color theme and keep the driver and passengers secure. As for the audio, forget it. There’s a stock system, but it’s doubtful that anyone looking at this car will care. It’s built to show and go, and does exactly that.
The BMW aftermarket is a beautiful, but less commonplace. It’s a marque with extensive brand loyalty and a beloved history. The quality of workmanship of this Z4 M continues to turn heads of enthusiasts young and old, and resulted in one of the highest honors in the BMW tuning community when it captured the Best of Show at MFest VIII this year. The response was so good that Slek decided to make the kit available in both carbon fiber ($24,999) and fiberglass options ($14,000). If this is what a couple of college students can achieve while still in school, just wait until they get out into the free world. #pasmag
Vehicle: 2006 BMW Z4 M
Built by: Slek Designs, LTMW, HP Autowerks
Location: Long Beach, CA
Engine: BMW S54 Inline-6
Horsepower: 570 hp
Torque: 380 lb-ft
VF Engineering supercharger kit (Vortech V3-Si supercharger 8.5-9.0 PSI, cast intake manifold, slide-in air/water cooled cartridge)
Magnaflow (exhaust, tip)
Ksport Kontrol Pro coilovers
RSV Forge wheels – 19x10.5 (f), 19x13 (r)
Nitto Invo tires – 275/30 R19 (f), 345/30 R19 (r)
Ksport big brake kit – 8-piston calipers, 400 mm drilled & slotted rotors (f), 4-piston calipers, 380 mm drilled & slotted rotors (r)
Stainless steel braided brake lines
Slek Designs full carbon fiber body kit (front bumper, front fenders, hood, roof, doors, side skirts, rear hatch, rear quarter panels, rear bumper)
PPG Deltron 4000 clear coat
Status Racing (FIA-compliant carbon fiber seats, 5-point harnesses, mounts, sliders)
SAE Motorsports roll cage
VF Engineering, Nitto Tires, Status Racing, RSV Forge, Ksport USA