"In this entry, I touch on the backstory to the Vorsteiner collaboration and the R&D processes to creating the E92 CSL Carbon Trunk Redux. I unbox the pre-production unit and share my notes along with test fitting original accessories."
- Matt

The initial plan. 

Manufacturing a trunk is expensive; it requires numerous large molds, various inserts and cut outs along with experienced craftsmen to meet the high expectations of fitment and carbon quality. 

Additionally, the market is difficult: low quality replicas are abound. Most will find their low cost appealing only to be faced with eye watering paint & body invoices for what will ultimately be subpar fitment.

Finding a manufacturer with the expertise, risk appetite and production availability for this product development would be challenging. 

Originally, the trunk was to be manufactured by a German composite company. I had removed the trunk and sanded it down to 3D scan the ducktail for mold mock ups and to ship it to Germany.

Unfortunately, we had significant differences on terms and specifications, along with significant issues on other products we worked on in the past. 

I cut my losses, pulled the plug and went for the Hail Mary. 

Vorsteiner's return to classic M cars. 

In late 2023, Vorsteiner had recently released their E46 M3 CSL V20 AeroCollection, born out of a celebration of their 20 years in business.

You have to be good at what you do and continuously improve to around for 20 years. In my perspective, it was perfected and culminated with the development of their own Porsche restomod brand; Gunther Werks. 

In the backdrop, I had been informally chatting with Peter, the CEO of Vorsteiner, on various topics surrounding these cars and carbon parts. Chats eventually evolved and formalized when Peter supported the Phoenix's restoration with a OE+ CSL carbon bumper.

Their pre-preg carbon bumper for the E46 M3 was a prime example their continued success and learnings. It had various features redesigned to facilitate installation over the 1:1 replica of the original CSL bumper.

The fitment quality was a rare 10/10 - I was genuinely impressed. 

The REDUX. 

In parallel, Peter and I discussed other product ideas for the E9x M3 and I threw my Hail Mary. 

I had a replica trunk on hand, I had pre-orders with deposits, I had the car to test it on, Vorsteiner was the original manufacturer of the E92 CSL ducktail. The business case and the story was there. 

It all made sense eh? I certainly hoped it did. 

Most importantly, Peter was enthusiastic about supporting the revival of quality components for M chassis of yesteryears. I understand there are more fruitful, profitable use of their ressources - I'm grateful for Peter and his team for supporting this project.

As of early 2024, Vorsteiner would officially be re-creating the E92 CSL trunk carbon. 

The development process. 

Back in 2008, 3D scanning was not a thing for most manufacturers. Consequently, Vorsteiner did not have design archives to re-create the ducktail and the original molds had gone out of tolerances years back and had been discarded. 

We had to start from scratch knowing the main challenge was meeting the expectations of an exact recreation of the signature ducktail. 

My fiberglass replica trunk had one positive: its ducktail design was accurate. It was shipped out to California at Vorsteiner's production facilities to be used as a basis for creating the Redux trunk. 

In December 2024, Aria, a California E92 M3 owner, offered his car up for development work. He dropped it off at Vorsteiner for a week January to complete the first steps int the process.

Vorsteiner begun with creating a positive mold of the trunk to achieve the exact shape of the ducktail we targeted. The white trunk mold shows the craftsmanship required to sculpt the shapes of the trunk to the desired aesthetics. 

The pre-production unit. 

With the positive mold created and approved, the negative mold was created for the first pre-production unit in March. By April, the first pre-production unit was created and Aria brought his car back for internal test fitment.

From pictures sent over, the ducktail aesthetics and fitment quality appeared spot on. Still, I've been involved in enough product developments to reserve judgment until I have had my hands on it and fully painted & fitted to my personal M3 V8. 

A first look.

The exact trunk pictured above was shipped from California to Quebec by mid April for my review, fitment and final approval. The trunk was shipped by FedEx in a massive Vorsteiner branded box and properly packaged - it was without a scratch. 

Below are my notes from my first impressions. I also discuss the few options available to help you to spec your trunk for your build. 

Notes on the ducktail. 

The fundamental goal of this product is to obtain the signature CSL ducktail aesthetics on the E92. Reviewing its design was on top of mind - and I was impressed. The Vorsteiner ducktail design is tastefully pronounced and shaped.

Notably, the ducktail's width tapers off from outside-in as it rises in height towards the center line of the trunk. As a result, it naturally increases the overall height over the standard E92 M3 trunk. 

Comparing with the original E46 M3 CSL. 

In my opinion, the design improves upon the E46 M3 CSL's original. As a comparaison, below are pictures from the E46 M3 CSL carbon trunk.

You will notice how the ducktail's width tapers over a much shorter distance than the Redux CSL design. This attention to detail especially suits the E92's Bangle-era design. 

Vorsteiner's E92 ducktail design recesses the emblem into the ducktail unlike the original E46 M3 CSL. It's yet another subtle, tasteful touch. 

Notes on carbon work. 

The trunk is manufactured using pre-preg carbon cured in autoclave. It is the highest quality carbon manufacturing process and matches what BMW uses for the E92 M3's carbon roof and M performance components. 

The benefits are many: in this specific use case - it allows precise fitment, light weight and high tensile strength.

Vorsteiner has a peculiar tendency to work with 1x1 weave carbon over most commonly used 2x2. For example, all of their E46 M3 CSL components are all available by default in 1x1 weave.

In my experience, this is especially rare on large products with complex shapes such as a trunk as curvatures tend to deform 1x1 weave. On the E92 M3 V8, our carbon roof panel is 1x1, giving us the potential to match the weave pattern depending on final paint choices. 

Overall, the carbon work is supreme. The weave placement & alignment along with careful attention to seams differentiates the craftsmen that take pride in their work through finer details.

This is one of the greatest carbon part I have reviewed up close along the lines of Karbonius' CSL airbox and the latest 1:1 Carbon Mirror Caps.

Notes on internal design.

The impressive workmanship continues on the underside of the trunk. Of note, we opted to replicate the original metal trunk's underside design.

The primary goal is to retain fitment of all original BMW trunk accessories, creating a true OE+ trunk. The trunk features all the required cutouts for accessories, bolts and wiring harnesses.

The design also retains the reinforcements, stampings and bracings of the original metal trunk - increasing its rigidity. This is most useful if you're planning to run a wing on top. 

Notes on accessories fitment.  

Vorsteiner recommends that all accessories best test fitted prior to final paint & body work. It's sound advise and should be standard operating procedures by any aftermarket body panels. 

The wiring harness for the trunk goes through the passenger side cut out below. The shape of the cut out matches the original rubber sleeve to ensure a waterproof seal. 

The bolt holes and threaded inserts are positioned to perfectly match the original trunk hinges and fit with original bolts. 

The trunk's latch cut out is perfect. No adjustments were needed upon test fitting my original latch. The cut outs for the trunk's adjustable stop buffers are also perfectly executed. The rivet-style push pins fit snugly as seen below. 

The trunk has the small notches used to fit and align the inner taillights. They are critical to ensure overall alignment of the taillights with the trunk and quarter panels. 

As a reminder, the taillights are purely held to the trunk by the plastic bracket and its bolt - anything short of perfection means water infiltration and misalignment as I experienced on the replica trunk. 

The taillights fit perfectly [...] after some fiddling. You need to find the exact position you prefer, and tighten the bolt on the plastic bracket. This will be best sorted once the trunk is on the car. 

The Redux trunk also has the required cut outs to fit the trunk liner with original push pins. The holes are all perfectly aligned with the original liner. 

Lastly, the cut outs for the license plate lights and electronic handle are present. I could only test fit the handle for the time being as my lights were damaged attempting to remove them from the original trunk. 

I also did not test the license plate frame fitment, not the emblem. The trunk does not have cut outs for emblems like the original trunk. You either break the tabs and glue the emblem - or you mark, punch and drill the trunk. I'll likely opt for the former over the latter.

Notes on weight. 

In addition to aesthetics and strength quality, pre-preg carbon allows us to remove weight. However, the CSL design and decision to retain 1:1 design on the inside inevitably adds weight due to its large ducktail - weight reduction is not this trunk's primary purpose. 

Below is a table comparing the weights. 

Trunk	Weight (kg)	Weight (lbs)
OEM	13.4	29.54
OE+ Superlight	3.5	7.8
CSL Redux	5.9	13.0

 

Vorsteiner lived up to my expectations - and then some. The E92 CSL Redux trunk is a beautiful piece through and through. 

Up next: I discuss the 2x finish options, we perform a few paint tests and finally test fit the fully assembled trunk to my E92 M3.