In the world of classic cars, there are pristine private collections kept behind closed doors, and then there are legends. For decades, the vast and secretive collection of the late Rudi Klein belonged firmly to the second category.

Since 1967, his Los Angeles “junkyard” became a place of fascination, filled with everything from dust-covered Ferrari body panels to rare and historically important automobiles. It was never about perfection. The focus was always on rarity, provenance, and untapped potential, regardless of condition.

Now, for the first time in generations, this hidden collection is being revealed. RM Sotheby’s is presenting it in a no-reserve auction, giving enthusiasts and restorers a rare chance to bring these forgotten machines back to life. Each vehicle requires significant restoration, but for the right buyer, this is an extraordinary opportunity.

1. 1931 Mercedes-Benz 370S Mannheim Sport Cabriolet

The 1931 Mercedes-Benz 370S Mannheim Sport Cabriolet is an exceptional window into the world of pre-war luxury motor cars. As one of the few authentic survivors from an early era of motoring, it was tucked away from public view for decades, retaining the timeworn authenticity and undisturbed historical integrity that the flawless hand of modern restoration so seldom fails to tamper with.

Key Historical Features:

• Pre-war luxury engineering
• Straight-six engine configuration
• Manual transmission system
• Partial early restoration work
• Authentic period craftsmanship

Reflecting engineering of the time, when a motor car of the era is judged upon its sheer mechanical simplicity and quality rather than electrical complexities. This straight-six and manual gearbox combination defines an early era sporting luxury motor car where a mechanical and driver driven experience are the prime concern. Evidence of previous restoration work still remains evident.

It now sits in silence as a project, a machine preserved in time. The patina that each surface, panel and component carries speaks of long storage and abandoned projects, and it becomes clear what an opportunity it represents to those with an interest.

2. 1933 Horch 780 Sport Cabriolet

The 1933 Horch 780 Sport Cabriolet is a classic illustration of the early German luxury automobile, and a prime example of an automotive design from an era where skill in workmanship and the mechanical sophistication were of the utmost importance. Horch, in its history has been responsible for the construction of some of the finest and highest of regarded cars in existence, all designed and engineered to exhibit style, strength, and extreme attention to detail.

Historical Legacy and Preservation Highlights:

• Early 1930s German luxury engineering
• Long ownership and museum history
• High level of original preservation
• Handcrafted interior detailing
• Rare surviving pre-war example

Throughout its long life, this example has endured an interesting existence, residing both privately and for periods in museum storage. Both of these stages are reflected in its unique identity allowing it to have existed in a condition perhaps truer to the original than many overly restored classics and giving it huge value with the fact that much of its original material is intact. It is a Horch that will be best seen as an original survivor rather than an intensively restored classic. 

There is quality still evident in the subtle detailing of the bodywork, as with all original cars of its age and that of the original fit and finish inside the cabin. It should be seen by both collectors and restorers as an car where preservation is of key importance to future appreciation rather than a candidate for a full restoration.

3. 1935 Mercedes-Benz 500K ‘Caracciola’ Special Coupé

Among the most significant and desirable vehicles of this period is the 1935 Mercedes-Benz 500K ‘Caracciola’ Special Coup. Intimately connected with the renowned racing driver Rudolf Caracciola, this bespoke model provides an unparalleled synthesis of grand tourer luxury and racecar pedigree, demonstrating the engineering excellence and prestige that Mercedes-Benz possessed in the 1930s.

Motorsport Heritage and Collector Significance:

• Direct link to Rudolf Caracciola
• Special commission build specification
• Blend of luxury and racing influence
• Concours event recognition history
• Rare private-storage survivor

This 500K is quite rare and has an important historical record having been displayed at various major concourse events where it drew the interest of collectors. It was praised for its rarity, superb craftsmanship, and above all, its provenance. The design and engineering is indicative of the very latest of thinking in automotive circles at the time, utilizing the design concept of the supercharged ability to attain a significant level of performance but within a fully equipped, and appropriately opulent, luxury model from Mercedes-Benz. 

Having been kept secret for so many years in private storage, it is again in the public domain and as a result of its great rarity and connection to one of the heroes of the sport, is of unique interest. Considered by pre-war automobile experts to be one of the most important survival finds.

4. 1937 Horch 853 Cabriolet

The 1937 Horch 853 Cabriolet is a classic representation of the elegance and precision German engineering provided prior to the war, boasting beauty and technological excellence, along with significant world provenance. This vehicle’s story follows an extraordinary trajectory through beyond Europe, and in its heritage, relates back to American engineering excellence, with undeniable worldwide admiration for Horch’s fine engineering, in an age of ultimate luxury cars.

International Heritage and Restoration History:

• German origins with global ownership history
• Connection to American automotive leadership
• Earlier restoration work completed
• Later part of the Klein collection
• Elegant pre-war cabriolet design

This specific Horch has a unique, layered history of ownership which is fairly common within the global community of scarce, important classics. Following its use in Germany the Horch came to be connected with several prominent members of the American automotive community, which again exemplifies the tendency of significant pre-war luxury cars to make journeys across borders and between cultures within private ownership and through the vehicle preservation community. 

It has had at least one previous restoration while under other ownership, revealing that this particular 853 has been well cared for. It has resurfaced after a significant period out of public view to represent the perfect example of pre-war grace that it is; the graceful lines and majestic proportions that speak to the automotive culture that has passed before. Within the greater Klein collection, it represents an exemplary symbol of the era of luxury driving, showing craftsmanship, heritage and artistry, with enduring appeal.

5. 1938 Maybach SW38 Sport Cabriolet

This 1938 Maybach SW38 Sport Cabriolet, despite its almost-certain industrial pedigree, offers one of the most idiosyncratic ownership histories you could imagine. Where many collectors’ items trace their ancestry back to the machinations of industry or to the upper crust of the aristocracy, this particular Maybach found its initial, perhaps even most characteristic owner in a German circus promoter, lending it an unusual, flamboyant, and entirely artistic aura.

Artistic Heritage and Preservation Details:

• Originally owned by circus impresario
• Distinctive Adriatic Blue finish
• Partial original paint preservation
• Period mechanical updates
• Blend of originality and modification

The car’s identity is much tied to its fantastic Adriatic Blue finish which allows it to be both imposing yet unique at the same time. Having survived the years there are a few patches of original paint remaining, which are also lovely and link it more with its original life. While this shows it was kept with a degree of care throughout the years, the old paint helps to retain its authenticity and quality, a trait not to be dismissed at the pre-war Maybach level of quality.

Throughout its years, further mechanical changes would have been made, as has occurred with many classic cars over their lifetimes. A mix of factory original features and later modifications, this gives the car a real complexity to it. It is both an aristocratic cabriolet and an old vehicle at the same time.

6. 1939 Horch 855 Special Roadster

This 1939 Horch 855 Special Roadster is by far one of the most valuable and rarest discoveries in this collection with all documentation pointing towards the fact that it could be one of, if not THE only surviving Horch 855 ever built. Unrivalled in its rarity this car is not just a remarkable collector’s piece but an incredible post-war automobile.

Rarity, Cultural Presence, and Restoration Legacy:

• Possibly the only surviving example
• Featured in historical publications
• Appeared in mid-century films
• Professionally restored in Germany
• Fully preserved pre-war masterpiece

The Horch 855 possesses a unique cultural significance beyond its purely mechanical relevance. The appearances of this particular car in print and cinema, beginning in the mid 20th Century and continuing until present day, have cemented its reputation as a documented artifact with a name familiar not only to hobbyists but to automotive history in general. Both automotive history and cultural archives recognize this significant automobile as having existed through several key eras in the development of modern transport. 

It was subsequently, meticulously, restored in Germany, by experienced professionals dedicated to bringing the car back to original specifications while retaining the spirit of the original craftsmen that produced it. Today, the restored automobile can be seen as a pre-war masterpiece.

7. 1956 Mercedes-Benz 300SL Alloy Gullwing

Among the collection’s assets, the 1956 Mercedes-Benz 300SL Alloy Gullwing stands out and is considered by many to be the highest-value vehicle in the lot. With this ultra-lightweight example-among the first off the line-it exemplifies the most extreme expression of Mercedes-Benz engineering ambition in the post-war era: innovation and performance combined with uncompromising design.

Rarity, Motorsport Heritage, and Engineering Significance:

• Ultra-rare lightweight alloy construction
• Limited early-production example
• Strong motorsport ownership provenance
• High historical and collector value
• Iconic post-war sports car status

Incredibly significant to this specific example is its all-alloy body. This make the car exceedingly rare compared to the more common, steel bodied cars of the subsequent, two years. Its construction shows Mercedes-Benz’s concentration on racing derived engineering, with styling inspired by the sport of motorsports and efficient aerodynamics, which together, had already seen the 300SL considered one of the most technically advanced sports cars in the world. Not least in its significance, it can be fully documented by its ownership, and that of a famous personality of motorsport. 

It has suffered relatively minor panel damage, in accidents which may have been encountered during the periods of extended storage. However, the car remains in absolutely all-original specification, and is without question one of the most significant post-war sports cars to exist.

8. 1957 Mercedes-Benz 300SL Roadster

The 1957 Mercedes-Benz 300SL Roadster stands for the ultimate development of the legendary Gullwing platform and translates the radical design of the original coupé into an approachable, and ergonomically improved open grand tourer. Although it retains all the performance heritage of the Gullwing Coupé, the Roadster leans more towards practicality, stability, and all-round comfortable touring capability.

Evolution, Rarity, and Collector Appeal:

• Open-top evolution of Gullwing platform
• Limited production specifications
• Rare competition-style wheel configuration
• Low-mileage preserved example
• High collector desirability

In order to offer an even more exclusive and refined version of their revolutionary sports car, Mercedes-Benz modified the gullwing 300SL into an open-top roadster. Despite a more practical approach (with conventional doors), the car managed to retain the characteristics of a genuine performance sports car. It remains a refined yet very capable vehicle, appreciated by both enthusiasts and collectors.

The car is equipped in original specification and more unusually fitted with a set of racing-style wheels, making this example particularly special with regards to historical significance and collectibility. The relatively low mileage combined with its care through years of storage ensures that the condition remains fairly impressive today, with several stints having been kept in good mechanical order by specialists in periods when it wasn’t being used. It remains today a chance to drive perhaps the finest Mercedes-Benz post-war production model that the firm has ever built, having been extremely well preserved.

9. 1959 Porsche 356A Carrera 1500 GS/GT Coupé

The 1959 Porsche 356A Carrera 1500 GS/GT Coupe is perhaps a better illustration of early Porsche philosophy than any other early model; built as it was in an era in which Porsche was fully developing its identity through the crucible of endurance racing, the 356 Carrera embodied perfectly the connection between racing and road.

Racing Heritage, Rarity, and Restoration Value:

• Motorsport-inspired engineering design
• Rare Carrera 1500 GS/GT engine configuration
• Extremely limited production numbers
• Strong endurance racing influence
• High-value restoration candidate

Here you see a Porsche that was designed from the ground up to provide high performance, with engineering features coming directly from the race track. The Carrera name shows its pedigree and the 1500 GS/GT specification of this particular car takes it even higher up the exclusivity scale. As very few 1500 GS/GTs were built it becomes all the more attractive for the discerning Porsche collector and historian. 

After years sitting static in a storage building, we have this challenging but immensely satisfying restoration project to undertake. Despite its unworked condition, originality and mechanical importance are assured. This 356A Carrera would surely provide the perfect foundation for a classic Porsche.

10. 1962 Porsche 356B 1600

The 1962 Porsche 356B 1600 is an outstanding survivor, respected for it’s unique degree of originality and remarkably low mileage. While so many classics are the subject of multiple restorers, this one has been untouched for over 50 years to maintain it’s factory character.

Originality, Preservation, and Historical Value:

• Extremely low-mileage survivor
• Near-factory original condition
• Long-term untouched preservation
• Used as a restoration reference benchmark
• High historical authenticity value

Instead of being restored this Porsche served as a base point of reference for other restorations, so to keep other restorations as accurate as possible. The original materials, finishes and factory settings of the untouched Porsche could be viewed so that they would be more easily recreated on other restoration jobs, its an interesting thought that this car served not just as a collectible piece but as a historic record to help recreate the correct settings of others, in effect helping other restorations remain ‘true’. 

The 356B 1600 remains today a revered, factory original Porsche, one which doesn’t represent a restoration but a survival of how Porsche produced the 356. If work had to be carried out it would be done so as to preserve this originality.

11. 1964 Iso Grifo A3/L Spider Prototype

The 1964 Iso Grifo A3/L Spider Prototype is a rare and highly significant example of cross-cultural automotive innovation, combining American engineering influence with Italian design artistry. Developed by Bertone, this prototype reflects a period of bold experimentation when manufacturers were actively exploring new proportions, styling directions, and performance concepts.

Design Innovation, Exhibition History, and Exclusivity:

• American-Italian engineering collaboration
• Designed and built by Bertone
• Featured in major 1960s motor shows
• Advanced experimental styling language
• Single one-off prototype

This unique Iso Grifo prototype emerged during a transformative era in automotive design, when manufacturers were pushing boundaries in both aesthetics and engineering. Its combination of American V8 influence and Italian coachbuilding resulted in a distinctive character that stood out at major motor shows throughout the 1960s. The vehicle attracted significant attention for its proportions, styling, and forward-thinking design language, which still appears modern even by today’s standards.

As the only example ever produced, the A3/L Spider Prototype holds unmatched exclusivity. Its rediscovery carries considerable importance for collectors and historians alike, particularly those focused on rare prototypes and one-off design studies. More than just a concept, it represents a tangible piece of automotive experimentation, capturing a moment when creativity and engineering ambition converged without limitation.

12. 1967 Lamborghini Miura P400

The 1967 Lamborghini Miura P400 is widely regarded as one of the most important automobiles in history, often credited with establishing the blueprint for the modern supercar. As an early production example, it holds significant historical value within Lamborghini’s legacy and represents a turning point in mid-engine performance car design.

Historical Importance, Condition, and Restoration Potential:

• Early production Miura P400 example
• Foundational supercar design influence
• Mid-engine layout innovation
• Incomplete but identifiable survivor
• High-value restoration opportunity

Even in an incomplete state and missing several key components, the Miura’s identity remains instantly recognizable and culturally powerful. Its design represents a revolutionary shift in automotive engineering, where the engine was moved behind the driver to improve balance, handling, and overall performance. This concept became the foundation for nearly every supercar that followed.

Although restoring such a vehicle would require exceptional expertise, time, and resources, the result would be extraordinary. A properly restored Miura P400 is not just a rebuilt classic it is a revival of a defining moment in automotive history. As a result, this example remains one of the most iconic and desirable restoration opportunities in the entire collector car world.