Cadillac
V-16 Sedan Cabriolet 'Madame X' (style 4155S) by Fleetwood

Why it matters

Style 4155S was the sedan cabriolet version of the 'Madame X' closed bodies Fleetwood built for Cadillac's first V-16 chassis. About seven are believed to have been made, and the car RM Sotheby's sold in 2014 is the only known survivor of the style.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

Production

Every figure says what it counts.

Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.

History

Cadillac unveiled its V-16 on 4 January 1930 at the National Automobile Show in New York. The 4100-series Fleetwood bodies that enthusiasts later called 'Madame X' – a name taken from a stage play and never used by Cadillac – were marked by steeply slanted 18-degree windshields and slim chrome-edged pillars. Style 4155S was a five-passenger sedan cabriolet with a padded, leather-covered 'convertible-look' roof, built at the Detroit Fleetwood Works.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Identification guide

How to tell an original from a replica or later conversion.

Look for the Fleetwood style number 4155S, the 4100-series 18-degree slanted windshield with narrow chrome-edged pillars, a padded leather-covered formal roof with landau irons, and a rear-mounted trunk and rack. The surviving car is body No. 2 with engine No. 702054, retains its original engine per its build sheet, and is likely the first built at Detroit Fleetwood with a one-piece windshield.

Sources

Each number links to the exact facts it supports.

1. 1
   RM Sotheby's Hershey 2014 – 1930 Cadillac V-16 Sedan Cabriolet 'Madame X' by Fleetwood Level B

   • 7 believed built in this style (one survives)

   Accessed 2026-11-11
2. 2
   1930 Cadillac V-16 Sedan Cabriolet 'Madame X' by Fleetwood (Hershey 2014, lot 151) Level B RM Sotheby's

   • 452 cu. in. OHV V-16 engine
   • 452 cu. in.
   • 185 bhp, 452 cu. in. OHV V-16
   • Three-speed manual
   • Wheelbase: 148 in.

   Accessed 2026-11-11