Pre-production cars typically live a short, abused life. Used to sign off last-minute tweaks and tuning, and even abused on TV programs (and some blogs) for videos and photographs, they’re sent to the crusher after just a couple of years. That should have been the case with this Kia Stinger, but delays in the required paperwork gave birth to an unlikely project: a one-off track day version.

Completed with the help of the Hyundai Motor Europe Technical Center in Rüsselsheim, Germany, this track day Stinger, christened the Stinger GT420, beefs up the output of its 3.3-liter twin-turbo V6 from 370 horsepower and 510 Nm of torque to 422 horsepower and 560 Nm of torque.


To do so, the powertrain team used HKS M45il spark plugs for enhanced combustion, a K&N sports air filter, and a lightweight Milltek Sport quad-exit exhaust system with its catalysts removed. Meanwhile, the 8-speed automatic gets a six-row transmission cooler (in place of the factory four-row one), while the transmission software is recalibrated for quicker shifting characteristics.

Aside from raw power, Kia stripped out the Stinger, the seats and belts, airbags, sound system, interior trim, and rear window regulators. The engine cover, undercovers, parking sensors, boot and hood dampers and rear bumper beam, and foam were also taken out, while the rear windows were glued into place and lightweight door cards installed. The Stinger’s sunroof was removed and replaced by a steel panel, shaving off a few more vital kilograms, even after a honeycomb panel was grafted in to add essential reinforcement to the panel. There is a total weight reduction of approximately 150 kilograms after the installation of the roll cage, seats, belts, and fire extinguisher.



A custom roll cage was installed and painted and the crash pad and necessary electronics re-assembled. Underbody stiffening comprises of a cross bar at the front and a pair of bars at the rear. With the roll cage in place, a pair of Sparco race seats were bolted into place. Completing the weight saving measures, a Lite Blox LiPo battery is installed to replace the original item, saving 22 kilograms.

The weight saving continues with the fitment of wider OZ Racing Leggera rims saving approximately 5 kilograms per wheel, and Pirelli Trofeo R tyres were selected for maximum adhesion on the track – 235/35/R19 at the front and 265/30/R19 at the rear. The camber angle was increased to -2.5 degrees by modifying the front cross-member, and uprated front brakes saw Brembo six-pot calipers and racing steel flex pipes fitted, along with high performance 380 x 34mm discs and Endless pads. At the rear, the standard Stinger V6 brakes were utilized. Cooling ducts and deflectors make sure that the brakes have the maximum cooling capacity needed on the race-track and tweaks to the anti-lock brakes, traction control, and electronic stability control ensures that they deliver optimum performance for on-track use. In Sport+ mode and by switching the traction control and electronic stability control off completely, the ‘Stinger GT420’ becomes easy to drift.


The standard dampers were used for the racing set up, with Eibach Pro lowering springs and anti-roll bars of 25 millimeters at the front. At the rear, an 17 millimeters in-house anti-roll bar was fitted. The continuous damping control was axed in favor of a conventional damper set up with some fine tuning.

Once the mechanical changes were complete, Kia then added some visual touches to the Stinger GT420. It features a Stillen front splitter and rear diffuser were added, along with a rear spoiler by Air Design. A special wrap completes the package.

Naturally, the question of cost arises. Unfortunately, Kia doesn’t want to say how much the Stinger GT420 cost, but given that most of the parts (probably except the rollcage) are off-the-shelf tuner parts, it’s completely possible to transform any Stinger into a formidable track day machine.