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1925 Rolls-Royce Phantom I Aerodynamic Coupe by Jonckheere (The 'Round Door' Rolls)
Rolls-Royce Phantom I with coachwork by Jonckheere
1925 (Chassis) / 1934-1935 (Bodywork Modification) · One-off Bespoke Coupe / Art Deco Masterpiece
Rarity Score
10/10 - Unicorn. There is only one in existence.
Spot Difficulty
10/10. It is a permanent resident of the Petersen Automotive Museum in Los Angeles. It does not travel frequently and is never 'daily driven' in the wild.
Engine & Performance
Engine: 7.7-liter inline-six; naturally aspirated; overhead valves; approximately 100-108 horsepower.
Transmission & Drivetrain: 4-speed manual transmission; Rear-Wheel Drive (RWD).
Performance: Top speed approximately 80-90 mph; acceleration is secondary to presence; curb weight is significant (approx. 5,500-6,000 lbs).
Exterior
Deep gloss black finish with Art Deco styling. Features distinctive circular doors, a sloped aerodynamic tail with a prominent fin, dual sunroofs, and a massive waterfall-style grille. Solid disc wheels with chrome hubcaps.
Interior Features
Red leather upholstery, fine wood veneers, Art Deco instrumentation, and a luxurious cabin designed for grand touring in the early 20th century.
Condition Assessment
Excellent (Concours Level). The vehicle is part of the Petersen Automotive Museum collection and is maintained to museum standards.
Condition Issues: None visible; preserved in a climate-controlled museum environment. Minor dust or fingerprinting from public display is the only plausible concern.
Estimated Mileage: Undisclosed, but likely very low post-restoration; primarily used for exhibitions and shows.
Historical Significance
A landmark of Art Deco design and automotive coachbuilding. It originally started as a standard Hooper-bodied Cabriolet before being rebodied in Belgium. It won the Prix d'Honneur at the 1936 Cannes Concours d’Elegance.
Notable Features
The perfectly circular doors, a longitudinal stabilizing fin on the rear trunk, and the absence of traditional door handles (operated via a pocket-watch-like button).
Production Numbers
1 of 1 unique coachbuilt body.
Valuation
Estimated Market Value: Priceless / $5,000,000 - $10,000,000+
Auction Estimate: Highly speculative due to its one-of-a-kind nature; likely to exceed $7 million if ever offered at a venue like RM Sotheby's.
Maintenance Recommendations
Specialized curation including fluid stabilization, periodic engine cycling, and paint preservation using high-grade carnauba waxes.
Fun Facts
It was once used as a roadside attraction in the 1950s (painted gold at the time) before being rescued and restored. The circular doors require the windows to be split into two halves that open like a fan. It is often cited as one of the most beautiful and mysterious cars ever built because the original design records from Jonckheere were destroyed in a fire.
Identified on: 4/8/2026
This AI-generated identification is for informational purposes only. It is not a substitute for professional evaluation. We assume no liability for decisions made based on this information.Read full disclaimer