Today we're used to seeing knockoff cars from China, but back in the early decades of the automobile, some of the (now) most established names in the industry stole from one another. This is the case of the Opel Tree Frog.
Yep, the Tree Frog. Technically, this car was called the Laubfrosch, debuted by Opel in 1924, five years before they sold themselves to General Motors. It got the name because the car was painted exclusively in a rich green.
Well, that's the official company line.
You see, the Opel Laubfrosch was nearly a carbon copy of the contemporary Citroën 5CV (pictured above, yellow) being built just over the border in France. The Opel was so similar to the Citroën, in fact, that Citroën sued Opel for stealing their design. Take a look at the two torpedo-bodied two seaters and you'll see that there's more than a passing resemblance between them. I will point out that the Type-C Citroën debuted in 1921, three years before the Opel.
Amazingly, the court rejected the case because the Opel had a differently-shaped radiator grill and because of that green paint. Citroëns were typically painted yellow, whereas the Opel was green! Totally different.
It should be noted that the courts that rejected the case were German.
This was no small issue at the time — Citroen ended up making 80,000 of their 5HP Type-Cs and Opel made not quite 120,000 of their Tree Frogs, enough to capture 40% of the German car market, as Ulrich Wengenroth writes in Big Business and the Wealth of Nations.
Interestingly, it's possible that the German phrase "the same, but in green" (that something being presented as different isn't really different at all) actually stems from the case of this '24 Opel. It's also possible that it all started with a 1903 cartoon about train tickets, as this German Wikipedia page notes, but the Opel could've popularized the saying.
So if you think that copycat designs are some kind of Chinese exclusive, remember the Opel Laubfrosch, and know that there was a time when the biggest names in the business were just as foxy.
If you happen to read German, you can read more about this case right here at 1300ccm.de.