John Castle, better known as the most knowledgeable E9 expert in the UK, ran the Register at the BMW Car Club GB for nearly 20 years. Since handing over the reins, he has continued to share his knowledge with the community through contributions to the newsletter and direct support to his successors. For the inaugural edition of CS COUPE, he kindly offered to be the first guest writer. His choice of subject: How did the Batmobile get its wings?

In the 1960s, under the direction of Paul Hahnemann, the Sales Director who had been recruited from Auto Union in October 1961, BMW developed the image of building “driver’s cars” by having an active competition programme. It was a successful theme, and privateer/works assisted BMWs were regular winners in many national and European competitions. At the time, it was all about “horsepower”, and with Alexander von Falkenhausen in charge of engine design assisted by his protégé Paul Roche, the company’s success was based on the 4-cylinder 2-litre M10-derived engine in rallying, saloon cars and Formula 2 single-seaters. This meant that in 1969, when the E9 was introduced, the factory was so heavily involved in supporting the 2-litre engines that it was decided to delegate the competition debut of the E9 CS with its new 6-cylinder 2.8/3-litre engines to Alpina and Schnitzer for competition preparation.  Shells were provided at a discount to various tuners who campaigned the 2800 CS and later 3.0CS from 1969 until 1972.  But without factory support the CS was regularly beaten by special lightweight racing versions of the V6 Ford Capri RS which Ford, with their massive financial resources, was able to homologate by producing 1000 cars whenever a new version was required.

By 1970, Paul Hahnemann was having increasing difficulty getting Board support to fund BMW competition work and in October 1970, the Board lost patience and declared that “BMW had called a halt to racing”. Hahnemann then fell out with his fellow Board members on a number of other key strategic issues and was summarily dismissed in 1971 to be replaced by Bob Lutz, an American, who with eight years experience with General Motors, was a strong advocate of production car racing to sell cars to the public. Lutz set about improving the performance of the CS by obtaining finance for a proper racing department. In May 1972 he poached Jochen Neerspatch and Martin Braungart from the Ford Competition Team in Cologne and won the funding to produce a lightweight version of the CS, the CSL.

By then, Alpina, and to some extent Schnitzer, had already encountered some aerodynamic shortcomings of the E9 design. At racing speeds above about 70mph, the CS lifted at the front, and Alpina introduced the first chin spoiler.

On fast, long right-hand corners, the wet sump oil was thrown out towards the left-hand side of the sump, starving the oil pump and leading to bearing failures. Alpina produced a gas-filled “recuperator”, which stored engine oil under pressure to maintain engine oil pressure whenever the pump pressure faltered. This led BMW to introduce an oil sump baffle plate for all over 3-litre production engines. Racing improves the breed!

These developments improved the reliability of the 2800 and 3.0 CS competition cars but not sufficiently to narrow the power-to-weight gap of the far lighter Ford Capris.

In 1971, the Karmann plant experimented with and produced a number of lightweight shells. Some of the outer panels were pressed from lighter SWG 22 instead of SWG 18 gauge steel sheets, whilst door frames, door skins, and complete bonnets and boot lids were pressed from sheet alloy. This is not as simple as it sounds because folding metal sheets thins out the metal at the corners so that it tears. It probably required quite a few trials in the pressing shop, and BMW stated later that series production of CSLs was finally able to start in December 1971. 169 lightweight shells were produced for selected customers on a random basis (with left-hand drive CS VINs), and in early 1972, Lutz was able to set the aim of getting the CSL properly homologated for Group 2 competitions for the 1973 season when he secured Board approval to start a run of 1000 CSL shells, 500 left-hand and 500 right-hand-drive. Production of the 1000 shells started in September 1972. The competition department had been allowed to take 21 of the early pre-production lightweight shells soon after Neerspatch and Braungart had arrived in May 1972 in order to develop the competition components required for racing and to prepare three team cars for the 1973 season. Homologation papers were submitted to the FIA, which stated that 1000 production CSLs had been completed by 28th November 1972. It is likely that BMW was being economical with the truth and must have been counting ahead because CSL production continued well into 1973, as will be explained later.  Of the first of the 21 bare shells, VIN 2276000 was used for development and first took to a track at Hockenheim in December 1972 driven by Tonie Hezemans for tests. The first competition outing for the team cars, VINs 2275999 and 2275998, was on 25th March 1973 at Monza, but both cars had head gasket failures, and the race was won by an older Alpina-tuned car. At the next outing on 20th May 1973 at the Saltzburgring, a lone team car had an engine failure and BMW’s honour was saved by Alpina and Schnitzer CSLs, coming second and third, respectively. The failure of the team cars was not well received at Board level.

So, whilst Paul Roche worked to solve the engine reliability problems, Braungart had spotted an amendment to the FIA Group 2 regulations. As originally issued, the regulations prohibited body alterations “above the midline of the coachwork”. However, the manufacturers competing in Group 2 events pointed out that this meant they had to produce 1000 new production cars just to incorporate even the most minor aerodynamic modifications before they could be used for competition. Braungart knew only too well that aerodynamics were going to play an increasing role in competition car performance. BMW had already noted the work of Ralph Broad, running the Broadspeed Team in the UK, who was recognised as an expert on car handling and in the developing science of wings, fins, and spoilers. In early 1972 the company had sent two CSL shells to Southam, in Warwickshire, which were extensively modified and had transformed the handling of the car in several races until declared illegal by the scrutineers for Group 2 races. Among the Broad modifications was a full-width front spoiler to replace the Alpina chin spoiler, which significantly reduced front-end lift and remains unchanged even today.

As a result of the manufacturers’ lobbying in early 1972, the FIA introduced an amendment which allowed bodywork modifications, provided that at least 100 “kits” were sold to the general public. Braungart used this change and took one of the team cars secretly to Stuttgart University over one weekend, which had a full-sized wind tunnel, for testing. Using hand-crafted wings, fins and boot spoilers, they tried various configurations until they had converted 60kg of lift at the rear at 200km/hour into a downforce of 30kg. “Alteration 1648/3/1E” to the CSL homologation papers was drafted by the 8th of May 1972 and submitted to the FIA on precisely the deadline of 6 weeks before the mid-season date of 1st July 1973 when the changes would be allowed on the track.

Later Braungart admitted that the submission (included below) had been prepared in great secrecy and submitted on the last possible date to make sure Ford did not get wind of the changes. At the same time, “Alteration 1648/4/3V” was also submitted which covered the engine upgrade to 3.2 litres and the introduction of 4 valves per cylinder.

The aerodynamic aids were used for the first time during practice for the 6-Hour Nürburgring on 8th July 1973, and Hans Stuck took 15 seconds off the previous best lap time for the CSL. In the race, the two team cars, 2275998 and 2275997 (a new, 3rd team car), finished first and second, convincingly trouncing the Fords. From then on, the CSL became almost invincible. Ford was furious at what they called “the deception” and, by the end of the season, decided to withdraw the Capri’s from the European championship.

In order to comply with the FIA regulations, BMW had to show that 100 “kits” had been sold to the general public by July 1973.  In May 1973, production of the 2275— series of left-hand drive CSLs had only reached 429, leaving 70 shells to complete the 500. So a further 39 shells were ordered to bring the total up to 109 cars, and production continued until June 1973, with the spoilers, fins, and wing sold to customers in a box found in the boot. To meet safety concerns raised by the TüV authorities, the boot spoiler, both fins and the wing were fitted with rubber trailing edges, and the customers were free to fit the parts or not. The front spoiler and black GRP rear bumper were part of the original left-hand drive CSL specification and remained unaltered.

And so, the “Bat” was born.

To sell the new version of the CSL, BMW issued a new brochure (note the different cars with HH–MN 27 with a full-width boot spoiler but no wing or roof hoop in the picture). No right-hand drive versions were built.

The team found over time that the downforce generated by the wing buckled the alloy boot lid, so a further alteration, 1648/13/3E, was submitted on 1 November 1974 for a three-fin wing fitted to a steel boot lid as used on the CSi.

Ford experimented with wings on the RS, but managerial inertia within the company ensured that they were never homologated, and the Capri fell out of contention during the remaining competition life of the CSL.

Homologation of the front wing splitters, the roof hoop, and the rear fins, wing, and boot spoiler led to the almost immediate modification of every CS competition car in existence. This has resulted in the description of nearly every CS race car since then being offered for sale, whether lightweight with alloy bonnet, boot, and doors, or just an all-steel shell, as a “Batmobile”. As a rough estimate, about 80 competition “Batmobiles” or more are posing for recognition.

“Imitation is the sincerest form of flattery that mediocrity can pay to greatness.” – Oscar Wilde