If you look around at, for example, the ST4 scene in Northern California, it’s pretty clear how you move to the front of the pack. If you’re a solid driver, you grab a BMW and fit it with an assigned set of parts from certain shops. But for Reto Baumann of Red Panther Motorsport, that wasn’t quite what he was looking for.

“If it’s that much of a recipe, why not just race in a spec category?” he cheekily asked. Then, with a pause for emphasis, he asked the philosophical question that doesn’t pass through enough club racers’ minds.

“Is that really the point of club racing?”

Is the MK5 GLI the most competitive platform? Certainly not, but there is something special about running an unusual platform in a highly competitive series like ST4 or the United States Touring Car Championship — and not simply for the ability to stand out and claim your moment in the spotlight.

Not to detract from the importance of individuality, but there’s more to picking out an odd racing car than mere personal expression. There’s a solid financial reason, too. “If I can stand out, it’s much easier to attract sponsorship,” Baumann clarified.

But it’s not as idealistic an aim as it might sound. After Baumann relocated to California from the East Coast, he got in touch with a Virginia-based racing team looking to sell a car that already checked a lot of boxes. This car came from the right place, was injected with high-quality goods, and destined for real competition.

This GLI rolled off the assembly line and went straight to Audi Motorsports USA Customer Racing, body-in-white and everything. It was set up with Ohlins coilovers, a professionally built cage, and plenty of other primo equipment to ensure it would be competitive at the Pirelli World Challenge races it was destined for. It was. The car earned GT2 class wins during the 2015 and 2016 seasons in the Sports Car Club of America. It also podiumed and won in Pirelli World Challenge before that. “That resumé ensured the car was built well, you know?”

He made an offer well below the asking price, adding that he’d be interested in chatting down the road if the other buyers backed out. Fortunately, they did and the owner was in dire need of shop space. The two struck a deal and Baumann took delivery of his first full-sized, full-on racing car.

As he already knew, the bones were good, but Baumann went ahead and made a few changes after the honeymoon period ended. Among all the changes, he replaced the springs with slightly softer ones, tweaked the aero package, and added an AIM MXG data logging system. It was a strong platform to start with, but it wasn’t without its headaches. Baumann would have to pass through a challenging teething phase before the GLI was truly competitive.

The wheel sports paddles with no external wires, which allows for complete removal.

Within a few months of purchasing the car, he’d just about had it with the powerplant, mainly due to the fact that, after the purchase of the car, the then-engine tuner left the US market, leaving Baumann without access to the tune itself. Then, the first time going to Auto Club Speedway, the cornering forces on the banking starved his motor of oil and set Baumann back even further.

Fortunately, and thanks to Life’s Good Racing of Livermore, CA, it only took him a few short weeks before he’d sourced and installed a new motor—and this time, he’d made sure he had a purpose-built racing oil pan from Poland with plenty of baffling to prevent oil starvation. He also added a second Accusump, through which he pumps Ravenol oil. Running the turbocharged motor in the California heat meant heat soak issues and the necessity of adding an additional CSF oil cooler and a larger radiator.

Having found a local partner in 034Motorsport in Fremont, Calif., an Audi and VW specialist, they together went on to address the tune and also added various 034Motorsport available performance parts to the car.

Considering All Aerodynamic Aspects

The area that drew most of his attention—and required the most of his creativity—was the one of wings and things. The car came equipped with the same wing that bolts to an Audi R8 LMS, so he was already set for most of the rear downforce he was after. However, he knew that to offset the car’s extra weight—about 400 pounds more than the fastest ST4 machines—he had to make sure the Jetta was generating as much downforce as his knowledge and the ST regulations would allow.

So to start with, he ended up lengthening the front splitter, which wasn’t quite delivering the front-end grip he was after. Now that it stretches all the way back to somewhere just before the front axle, the front end’s strong enough to allow him to lean comfortably on the car through faster corners like Buttonwillow’s Riverside and still maintain the intended line. Canards help there, too.

That dependability also requires a balanced backside. In this case, he supplemented the massive Audi wing with a rear diffuser that does more than just generate rear downforce. The exhaust funnels into the underbody, using some of the suction effect from the venturi to reduce backpressure in the exhaust and drag some hot air away from the rear brakes. This custom diffuser was the brainchild of Reto and Red Panther Motorsport’s Crew Chief, Chris Hovey. Hovey is also the shop manager at Life’s Good Racing where the work was done.

Now with this setup, you could be forgiven for thinking it’s a blown diffuser. Mainly because of noise constraints, the famously raucous blown diffuser wouldn’t have flown. But the reason this exhaust configuration doesn’t produce additional downforce is because it’s just a little too far downstream to accelerate airflow significantly.

Nevertheless, it demonstrates Reto’s interest in every aspect of airflow management. The front fenders help relieve the front wheel wells of the massive heat caused by a driven front axle, 280-width tires, as well as the Sparta Evolution six-piston brakes—which were designed and manufactured just for this car.

“We were just cooking the front tires at this point,” said Baumann. Cutting a careful opening in the rear of the over-fender helped release some heat from the impressive Sparta stoppers.

Getting those wide tires to fit snugly required a little widening courtesy of the Clinched over-fenders. These items feature a custom chop at the back of the fender, which is really just a part of a system that relieves pressure and heat from the front wheel wells and diverts air away from the underbody; therefore making sure the diffuser is well fed.

Even within the car, Reto’s taken some unusual approaches to utilizing airflow—even if it isn’t for the purposes of generating downforce. As per NASA and USTCC rules, the front windows must be lowered while driving. This causes turbulence inside the cabin, which is usually dispelled through a set of small, low-drag exits in the rear quarter glass—or whatever’s come to replace it. In this case, Baumann retained all the glass behind the B-pillar, and instead chopped a letterbox-shaped opening in the rear bulkhead. This feeds a secondary set of trunk-mounted ducts which further cools the rear brakes.

The fit and finish is obvious at first glance. It’s built to an unusually high standard. The smaller details — like the removable, paddle-equipped wheel, which lacks any wires — let you know you’re in something well thought-out.

Making the Most of a Modern Powertrain

The motor has been gone through in the last year or so to try to improve upon its low-revving, high-torque nature. Though the motor remains stock internally, its original K04 turbo was replaced with a Garrett Gen-2 GTX2860R—adding a good chunk of midrange and bumping output just shy of 350 horsepower at the wheels after a tune.

To stay in the powerband, the shift point is around 6,200—around 500 revs shy of redline.

That big surge of midrange torque and the original calibration of the engine made the Jetta a beast that was somewhat undriveable at first. Now, thanks to the 034Motorsport tune, there’s a manageable amount of torque steer still, but it’s less of an issue. Now the overly sensitive throttle has been dulled to make it more controllable, less likely to spike over a bump, and treat the front tires nicely.

You have to be extremely smooth with the throttle in slow corners, but as the speeds increase, it gets better. It’s stiff and the aero grip makes it a pretty nimble thing in the third and fourth-gear corners, and the amount of power is dwarfed by the growing levels of grip. That’s what makes it so fun to hustle.

It’s controlled by the standard DSG (direct sequential gearbox) from VW as used in the street car, a recent addition. Prior to this, a six-speed manual slowed shift times and forced Baumann to lift between gears. Now, he keeps the throttle pinned and capitalizes on that straightline advantage.

Putting Power to the Front Wheels

Where a paddle-shifted, front-wheel-drive car has the advantage over a lot of its opponents is leaving hairpins like Sonoma’s Turn 11. Some medium speed corners are still a problem—that’s where the RWD opposition has a distinct edge. If you think of how long the front tires are loaded in a corner like Sonoma’s Carousel, it’s not all that surprising that the Jetta’s not at its best there.

Currently, the car is set up to help rotate that rear. Because the bulk of the weight sits over the nose, it’s easy to unbalance the platform on corner entry. “I’m personally not really helping with the weight distribution much,” he says with a laugh.

How this differs from a RWD car in over-rotating is that you can plant your foot on the throttle and the car pulls you in the direction you have the steering wheel set. However, adding a bit too much throttle to settle the car can result in wheelspin at the front axle. Aside from damaging the tires and potentially causing a four-wheel slide, spinning the front wheels means that the rear won’t necessarily follow in line. The pulling force simply will not be there.

“You can’t just floor the throttle or it will spin up the fronts. If the wheels are spinning, then there’s not enough pull to straighten it out.”

“The car can be a little tricky, but it is generally very talkative and easy to drive. If you’ve never driven a race car before, it might be too much, but any moderately experienced driver should get up to speed fairly quickly.”

For 2022, Reto has a good list of further modifications to make to this car. He wants to trim weight, add air jacks, and get the active aerodynamics, something a little like DRS (allowed per USTCC rules), working properly. He also wants to change the fuel filler neck for quicker refueling and address the current pickups’ inability to scavenge the last trickle of fuel from the tank.

The biggest challenge however, will be stuffing 300-section tires into all four wheel wells. The added benefit to this modification, though, is that they’ll try to address the excessive heat caused by the massive Sparta brakes. “We’ve been studying the TCR cars and how they manage airflow. We’ll try and take a page out of their book with the new over-fenders we are working on.”

“Not everything has been peachy—not by a long mile,” says Baumann. “But there was success along the hard road as well. And those tasted sweet. Several race wins, consistent podiums, and Championship runner-up positions in USTCC are some of the car’s accolades.

More than results, Baumann draws great satisfaction from the way his Jetta grabs the attention of so many fans. It takes a special sort of car to lure IndyCar mechanics from their pits on a busy weekend to take a peek at a production-based racer—just as it happened one weekend when both USTCC and IndyCar shared a circuit. Had he been running a more conventional car, he certainly wouldn’t have enjoyed such a rare opportunity.

Though motorsports doesn’t promote individuality quite the way it used to, occasionally one unusual vehicle or free-thinking driver enters the fray and brings a little more color to the sport. Thankfully, Baumann has been able to capitalize on that energy and design a car that’s capable and characterful while still remaining a force to be reckoned with. If there were any naysayers claiming he’d been too concerned with self-expression, his rapidly improving results ought to silence them.

Image courtesy of Richard Pochop

2 COMMENTS

  1. If only it were so “easy” to just build a bmw and win. But in reality it isn’t. Many super touring drivers have put in the time and effort to get faster with coaching and lots of quality seat time. Let’s not forget the power to weight of st4 is significantly less than this car which would be classed in st2.

  2. Interesting that the article suggests this unique vehicle is classed as ST4 when shown with aero features that are miles from class compliant.

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