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At the Frankfurt Motor Show in 1955, BMW unveiled an all new sports car that was put in place to help continue the company’s post-war growth. The 503, as BMW dubbed it, went into production the next year and came in both a coupe and convertible model. Only 413 total 503 models were ever built and 139 of those were convertibles (cabriolet).

This makes the BMW 503 Series I Cabriolet one of the most desired BMWs of both its era and all eras, for that matter. The 503 was never an overly powerful model, but it was a well-balanced car that delivered performance and comfort at the same time – something that was lacking in the late-1950s.

With it only seeing a production run up until 1959, getting your hands on one of these gems is quite the tough task. It is not completely impossible, however, as there are a few that cross the auction block every handful of years. You can bet your bottom dollar on the fact that these rare 2+2 drop-tops fetch a rather hefty sum.

Click past the jump to read all about the 1956 through 1959 BMW 503 Series I Cabriolet.

  • 1956 - 1959 BMW 503 Series I Cabriolet
  • Year:
    1956- 1959
  • Make:
  • Model:
  • Engine:
  • Transmission:
    4-speed manual
  • Horsepower @ RPM:
    140 @ 4800
  • Torque @ RPM:
    159 @ 3800
  • Displacement:
    3.2 L
  • 0-60 time:
    12.8 sec.
  • Top Speed:
    118 mph
  • Price:
  • car segment:
  • body style:


1956 - 1959 BMW 503 Series I Cabriolet Exterior
- image 469004

The 503 definitely boasted one of the more advanced designs in a production 1950’s car. Up front, it has one slim vertical grille flanked by two smaller, horizontal grilles. The large, round headlights seat into rounded fenders that trace the entire length of the car’s front fenders. The thin, chrome bumper under the front end provided little protection, but it looked good providing the little protection that it gave.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469003

The hood has a very slow slope to it, giving the front end a more aerodynamic look. Down the center of the hood you get a chrome strip that divides the hood into two halves. This brings you to the steep windshield that offers little aerodynamic benefit, and is surrounded by chrome trim.

In an attempt to break up the monotony of the rather plain side of the car, BMW ran a chrome strip from aft to tail. This strip had a slight curve to it and a sharper upward turn near the rear of the 503, helping it achieve the task of sprucing up the car’s otherwise bland side profile. In what looks to be a connector between the front and rear bumpers, BMW added a chrome strip on the bottom of the car’s side that runs from one wheel well to the other.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469000

The back end boasts fender flares similar to those on the front, but slightly thinner. A chrome applique just above the license plate helps to keep the rear end from becoming dull. The 503’s backside boasts four light sets: one taillight and brake light combination and one reverse light. The taillight and brake light have a sharp, chrome applique separating them.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469023

Also on the rear end is an odd positioning of the muffler. BMW, in a fit of “where do we stick this” bolted the muffle to the body, just under the bumper, in plain sight. We can only assume that Bimmer ran out of space under the car.


1956 - 1959 BMW 503 Series I Cabriolet High Resolution Interior
- image 468999

The inside of the BMW 503 boasted two front bucket seats and a small, 2-seat jumper in the rear. To call it a 2-seat jumper is a little generous, but that was its intention. The features were very basic, as were most 1950’s cars. It did, however, boast a Becker Mexico AM radio, something not yet standard in every car built.

Engine and Transmission

1956 - 1959 BMW 503 Series I Cabriolet Drivetrain
- image 469002

The main concern for the 503 was to rid BMW of its aging 2.0-liter 6-cylinder engine. BMW manufactured the 503 to handle an all-new, aluminum block 3.2-liter V-8 engine with twin Zenith carbs that pumped out 140 horsepower at 4,800 rpm and 159 pound-feet of torque at 3,800 horsepower. Those aren’t staggering numbers, but in its time, they were pretty respectable for a small-displacement V-8.

1956 - 1959 BMW 503 Series I Cabriolet Interior
- image 469012

The engine connected to a 4-speed transmission that, as expected, threw power to just the rear wheels.

This combination could push the 503 to 60 mph in 12.8 seconds and gave it a top speed of 118 mph. Again, those aren’t impressive numbers by today’s standards, but by the late-1950s, those were very respectable numbers for a small roadster.


1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior Wallpaper quality
- image 468996

Like we always say with collectable and classic cars, they are worth exactly how much someone will pay for them. NADA books out a high retail value of about $137,000 for a base model 503 cabriolet. In real life, however, collectors are wiling to pony up a little more dough, as RM Auctions is selling a fully restored 1956 503 Series I cabriolet at auction and they anticipate it to go for $325,000 to $425,000.


1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469022

While the BMW 503 was not an overly fast or powerful car by today’s standards, it was very respectable for its era. In addition to that, it is also a key element in BMW’s return to glory following WWII. To boot, it is one of the rarest BMWs in the world, especially the cabriolet model.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 468997
  • Leave it
    • Low power output from a V-8 engine
    • A little on the heavy side
    • Huge price tag
Justin Cupler
About the author

Press Release

BMW 503 Series I Cabriolet

Chassis No. 69081
$325,000-$425,000 US
AUCTION DATE: To be auctioned on Saturday, August 18, 2012

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469021

140 hp, 3168 cc overhead valve alloy block and head V-8 engine with twin Zenith carburetors, BMW 507 four-speed manual floor-shift transmission, independent front suspension via upper and lower A-arms and live axle rear suspension with torsion bars, and four-wheel hydraulic brakes. Wheelbase: 111.6"

• One of a mere 139 cabriolets built
• Recent, professional body-off restoration
• Best Postwar BMW at Hilton Head in 2011

Like its rival Mercedes-Benz, BMW found itself in a tough postwar situation and needed to introduce a new model to gain the public’s attention. The 501 and its successor, the 502, were successful in achieving this, but the prewar six-cylinder engine was dated, and it was time for a higher specification model. Highly influential in BMW’s decision to market a V-8 was notable U.S. importer Max Hoffman, who used his talent for persuasion and the size of his distribution network to convince BMW that a luxury sports car for the top 10 percent could be sold in sufficient quantity. With engineering by Fritz Fiedler and styling by Albrecht von Goertz, the elegant 503 was introduced at the 1955 Frankfurt Motor Show.

1956 - 1959 BMW 503 Series I Cabriolet Exterior
- image 469004

Chassis 69081 was delivered new to the United States for its first owner, architect Emanuel Weisfeld in Laurelton, New York. It was subsequently purchased by well-known BMW enthusiast Barry McMillan, of Hilltown, Pennsylvania, in May 1976. In October 1979, he sold it to Dick Hamilton, of Arvada, Colorado, who acquired it as one of many projects that he was saving for his retirement. The car sat in Hamilton’s barn for the next two decades until being acquired by BMW specialist Don Dethlefsen, of the Werk Shop in Libertyville, Illinois, who became the car’s fourth owner in October 1997.

After about three years, Don had enough time to spend on his personal project, and he embarked on a thorough body-off restoration, which “left no stone unturned.” The ladder frame and superstructure with aluminum body was completely disassembled, such that no two pieces stayed together. It took well over a year to properly rework and treat the aluminum and steel body shell. The hand-hammered coachwork is finished with all of the correct original Series I trim. Aside from numerous hours spent making the body and paint just right, an additional $40,000 was spent replating the chrome.

1956 - 1959 BMW 503 Series I Cabriolet Drivetrain
- image 469002

Like the many European cars that were imported to North America and ill-equipped to deal with the additional heat, 503s often overheated. This example suffered a seized engine early on by the original owner, and the original 3.2-liter unit was first replaced by one that had been part of a batch of smaller 2.5-liter BMW engines supplied to Talbot-Lago and subsequently acquired by legendary racer turned dealer Otto Zipper. A four-speed floor shift transmission from a 507 had also been installed.

The engine currently installed is an original 3.2-liter 503 engine that was sourced from Germany and today, has approximately 14,000 miles from new. Like the rest of the car, the engine and its ancillaries were fully rebuilt. For the preceding reasons, the radiator is purpose engineered and larger than the original but now fully capable of properly cooling the engine. Although accuracy is important, it was paramount to the restorer that cars be functional as well as beautiful. Although the transmission in the Series I 503 was column shift and floor shift on the Series II, the 507 transmission was retained because it has better gear ratios and is a valuable piece in its own right. Aside from these two functional deviances, every other element of this car is perfectly stock.

During the restoration, all other chassis and suspension components were rebuilt or replaced. Even the original Becker Mexico radio was fully rebuilt to factory specifications and functions as it did when new. A good number of NOS parts were sourced from Germany, including the engine rebuild parts, brake parts, and some of the smaller detail pieces, like interior knobs.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Interior
- image 468999

The red exterior is complemented by a tan cloth top and tan leather upholstery with red piping. The English leather interior nicely complements the bright exterior, and the work is exceptionally presented, all the way down to the Wilton wool carpeting. The trunk is also fully reupholstered, as it was from the factory using the same “elephant hide” textured material that was originally used.

With fine details done to perfection and apologizing for nothing, this BMW 503 is remarkably complete and even includes the original tool box with its tool set, which is nearly impossible to locate. The photo-documented restoration was completed just days before its debut at the 2011 Hilton Head Concours d’Elegance, where BMW was the featured marque. The 503 was the recipient of one of the show’s highest awards: Best Postwar BMW. A restoration album was assembled using some of the many hundreds of photos taken throughout the restoration process and will accompany the car. The owner proudly claims that “this is the best 503 in the world at present.” Given that the production run of 412 units included only 139 cabriolets, it is hard to imagine anything better.

1956 - 1959 BMW 503 Series I Cabriolet High Resolution Exterior
- image 469023
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