I’m not sure if you know this about me, but I tend to have a number of slow-simmering automotive research projects bubbling around, often unattended. One of these has been my quest to figure out the origin of one of my favorite headlamp units in all of motoring: the sloping, chrome-rimmed, double-glass headlight used on Volkswagen Beetles from their 1938 design finalization to 1966 (in America, at least) and also used on the Porsche 356 and early (and a bit modified form) 911. It’s an iconic headlamp, and so far its origin has been a mystery, at least to me. But I think I have a clue now.

I bet most car dorks are aware of this headlight, as it does show up on some pretty well-known cars. The Beetle, of course, but the Type II VW Microbus used them too, just rotated 90 degrees, and of course the famous Porsches everyone knows.

It also appears on DKWs in the 1950s and 1960s, and on a few other smaller marques in that era, pretty exclusively German: Maico microcars, the Goliath GP700 Sports, and the outer lens is used on the DKW Schnellaster van, where it opens up with the hood, which is very weird and cool.

I should also mention, in the interest of full disclosure, that these headlights are one of my main go-to doodles:

They’re weirdly satisfying to draw, for some reason.

There are a few variants of the basic headlight: American-market ones with clear outer glass, an inner sealed-beam bulb, and a little parking light bulb set inside the housing, Euro-spec ones with fluted outer lenses, yellow French ones, Porsche-specific outer lens shapes, different adjustment screw locations, etc.

Some were made by Bosch, though in the U.S. we usually had Hella units, and I did reach out to Hella to see if it had any archives or records that could help shed some light on the origin of these famous headlights. It had nothing, though it did offer to send me a coffee-table book about their company’s history, even if it didn’t have the answers I needed, so that was nice of them.

I want to know where these headlights got their start, and, ideally, maybe even find out who designed them.

By far the most common very early images of these lights are on their use on the proto-Beetle, the , which had its design finalized by 1938, complete with the famous sloping lights. These headlights seem to be part of the final design, as prototypes from 1937 and earlier do not have them:

I believe these headlights weren’t designed or built by VW themselves, something I think can be proven in this picture of the 1000th Volkswagen built, when the factory was under post-war control by the British:

Look at those weird headlights! They appear to be the simpler, dune-buggy-like units from the Kubelwagen, set into the Beetle’s fenders and the extra space filled by a chubby torodial bezel of some sort. It always looked like it may be rubber to me, but I’m honestly not sure.

The point is, these first thousand cars were built immediately after the war, when the factory was partially in ruins and supplies of all kinds were scarce. I suspect that the usual supplier of the preferred headlights was unavailable, so the factory made do with what itcould, the results of which suggest that the VW plant was not the source of those headlights.

So, the famous lights must pre-date the 1938 KdF design, in order for them to be seen and selected for use on the car. But what car had them before the VW?

One of the earliest cars with similar lights is the Tatra T77, which had a number of headlight types while it was being built, but one of those designs does seem a possible candidate for an early inspiration.

The T77 was first designed in 1934 and built until 1937, and while it seems like no two pictures of these things has quite the same headlight setup, at least one had sloping lamps that at least resemble the VW/Porsche ones I’m interested in.

They’re not the same lights of course, but the aerodynamic car community in Europe in the 1930s wasn’t huge, and everybody was looking at everyone else’s designs.

My current theory is that the German company Adler’s designer, , had noticed the T77 and especially its sloping headlights, and used this car as inspiration for the Adler 2.5 liter (also called the Adler Typ 10, or, as a nickname, the Autobahn Adler) which was designed around 1936 and went into production in 1937.

Jenschke would have been aware of the Tatra since he worked under Tatra’s designer, Hans Ledwinka, while employed as an engineer at Steyr, where he designed a number of cars, including the streamlined, beetle-like .

The Adler looked an awful lot like the Tatra T77, and had a very similar front end with very similar close-set, sloping headlamps, though they flanked a grille, which was unneeded on the rear-engined, air-cooled Tatra but required on the more conventional water-cooled, front-engined Adler.

As you can see, the headlights look an awful lot like the units used on the VW, down to the little tab at the lower center. The outer lens design on some examples seems more like the fluted kind fitted to Porsches, but there also appear to be examples with simpler domed lenses closer to what VWs used as well:

Now, I’m not ready to say that this is final, conclusive proof, but I am willing to say that so far, the earliest car I can find that seems to have these particular headlights is the 1937 Adler 2.5 Liter, designed by Karl Jenschke. I think that these lamps were designed for Adler based on ones seen on the Tatra T77, and built by a supplier like Bosch or Hella, which then sold them to the Volkswagen factory when the KdF/Beetle’s design was being finalized.

If there’s any Adler mavens out there or anyone who has seen these lights on something earlier than 1937, I would love to hear from you. If my current theory proves to be right, then I’d say that would make these headlights Adler’s most enduring contribution to motoring, as they survived so much longer after Adler was gone.

Maybe if I can confirm this, Hella can stick it in their big old book, too.