There's a long tradition of American drivers missing out on appealing European cars. But that spawned another tradition of recreating these remarkable machines using a combination of ingenuity and sheer determination. There's also a third tradition of giving it a unique twist, with Audi's RS wagons commonly reinterpreted as more popular sedans.

Not wanting to break with this tradition, Dennis Tang teamed up with TAG Motorsports in Vista, CA to create the first B8 RS4 in the US, and the first B8 RS4 sedan in the world. This gives him huge bragging rights, and frequent sightings of the white Audi have led to online forums lighting up as enthusiasts imagine they've seen the automotive equivalent of Bigfoot.

So how did it all come about? Dennis has been modifying his 2013 Audi S4 ever since he bought it. In fact, it was previously featured in EC 11/13 as part of our "Coilovers vs Air" suspension test. Dennis had fitted the KW DDC and HLS system, allowing the damping rates to be varied on the move or from his phone, and the nose to be hydraulically raised to clear obstacles. It was a great comparison for the AccuAir air suspension and proved a worthy adversary in our test.

In addition to the suspension, Dennis had worked with Alex Andonian at TAG to fit AWE Tuning components such as GIAC software, StopTech big brakes and 19" HRE wheels. That was eight months ago, and a great deal has happened in the intervening time...

Playing TAG

So what does it take to build an RS4 sedan? We spoke to Alex about the build, since he'd been at the sharp-end of making it happen. "It started as a joke," he recalled. "We'd done almost everything possible to the S4 but without getting into the cosmetics too much. One day, Dennis asked what else we could do and we suggested the European RS4 as a joke!"

While it might have seemed ridiculous at the time, the seed was planted in Tang's brain and on his next visit, he asked them to investigate the RS4 conversion further.

"Dennis is a great guy and we became friends during the course of his S4 build. He was always dropping in to have something fitted or refined, so we were happy to look into the RS4 swap," Alex continued. "If we didn't have that relationship, we probably wouldn't have taken it seriously..."

Using two computers to compare S4 and RS4 parts lists and diagrams, the TAG team created a list of what they thought would be needed to build this very special car. The total came to around $23000 and, with regular shipments coming from Germany every three weeks, the parts were soon in their possession.

"It was when everything was laid in front of us that we fully realized the size of challenge," Alex admitted. What had seemed like an interesting notion was now an action list on a whiteboard.

With so much fabrication needed, Alex enlisted the help of local specialist, Hot Rods & Custom Stuff (HRCS) from Escondido, CA. These guys have created some incredible projects, including the "Mercedes Bent" from SEMA 2010 - it was a 190SL with SL65 running gear, built to an extraordinary standard and the star of the show. While they don't come cheap, Alex knew the quality of work would be beyond reproach.

S4 to RS4

Diving into the project, TAG removed the front-end in order to fit the RS4's flared fenders. And that's when the problems began. The S4 fenders are about 0.25" longer. Getting the new parts to fit properly would require new door sill sections - actually it needed a one-piece item that fits into the bottom of the door jambs, locating the doors, all four fenders and side skirts.

Aware that everything could be "made" to fit eventually, Dennis and Alex decided to do it right, ordering the new door sills and cutting out the S4 panels. Because they weren't structural, it didn't affect the bodyshell but would ensure the majority of parts fitted properly.

They weren't out of the woods yet. With the front fenders in place, the RS4 front bumper and grille rapidly followed (both cars share the same hood). The side sills went on and the front doors were good, but the RS4 is an Avant and the roofline is different at the rear. The solution was to order RS4 rear doors but remove the top window frame and replace it with the S4 frame and glass.

The flare for the rear fenders also starts in the rear doors, so they were needed anyway. However, TAG also discovered that the gas cap is contoured, so that was added to the parts list.

The rear quarter panels were obviously flared but, designed for the wagon, the shape continued higher and longer than it would on a sedan. So HRCS set about reshaping the panel to fit. Everything was done in metal so that the panel just needed to be attached rather than filled.

While working on the rear, they discovered the RS4 also has different inner fenders and floor area, so these parts were also ordered and welded onto the sedan to ensure a perfect replica.

At this point, everybody was looking forward to the project's conclusion. And then the rear bumper raised its ugly head. "This was probably the biggest headache of the entire build," Alex admitted. "It took 60 hours in labor alone!"

The problem was that the Avant's tailgate and light positions were utterly different to the sedan, so nothing was aligned. After careful consideration, the best solution was to graft the top of the S4 bumper to the bottom of the RS4 part, ensuring the original trunk and tail lights could be retained.

The S4 section then had to be flared to match the contours of the RS4 bumper, which continued the lines of the fender flare. The job initially involved heating and pulling, but would require some plastic filler as well to get a perfect finish.

"Perfect" is the right word to describe this car. Alex and the entire team went the extra mile to build something Audi might stand behind. "We aim to have it inspected by an Audi dealer once the shakedown tests are completed," he stated. "We want to assure Dennis, and anybody else who might want the same, that this vehicle is correct in every detail."

The original Ibis White is also a stock RS4 color, so the car was resprayed by HRCS to their exacting standards. The window surrounds and exterior trim were painted gloss black to replicate the Black Optic package on the RS4.

With no trunk spoiler option for the B8 RS4, Dennis retained his existing S4 part, which is tastefully discreet.

Thinking of building something similar? Alex estimated a cost of around $65k to replicate it to this standard, working with HRCS. But that's without wheels, brakes, suspension, etc.

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