Rising fuel economy and emission standards are threatening the V12 engine, but not that long ago BMW started development of a V16.

While 16-cylinder engines are rare and are commonly associated with Cadillac and Bugatti, that didn’t stop BMW from exploring the idea.

The story starts in 1987, when BMW decided to develop a V16 engine that was codenamed “Goldfisch (Goldfish).” The engine was based on the company’s existing V12 and had a displacement of 6.6-liters. That’s the same displacement as the V12 engine which resides in the current BMW M760i and Rolls-Royce Ghost.

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However, the old engine didn’t have twin turbochargers and only produced 402 hp (300 kW / 408 PS). That doesn’t sound like so much these days, but the V16 was a significant improvement over the 5.0-liter V12 M70B50 engine which resided in the 7-Series and developed 295 hp (220 kW / 299 PS).

Following the development of the engine, it was installed in an E32-generation 750iL, which was internally called the 767iL Goldfisch and “Secret Seven”. While this isn’t too surprising, the unit was so long that engineers were forced to install an extensive cooling system in the trunk. This resulted in an odd looking prototype that featured an open rear fascia and massive side scoops above the rear wheels.

After extensive development, the prototype was presented to the company’s “inner circles.” Unfortunately, they decided to pass on the idea and the V16 never entered mass production.

As for the company’s current V12 engine, it appears to be living on borrowed time. In June, BMW M boss Markus Flasch said “I don’t believe we will see a new twelve-cylinder model in the foreseeable future.”