In the world of supercars, there's always something trying to be different. Lamborghini gave us scissor doors. Pagani gave us interiors that look like they were designed by Leonardo da Vinci on hallucinogens. Ferrari gave us engines that sound like opera singers being electrocuted.

But only one car in automotive history has ever given us something from a submarine.

The Isdera Imperator 108i is perhaps the most gloriously bonkers supercar you've probably never heard of. And that's a tragedy, because this is automotive history on wheels. A car so rare and so bizarre that it makes owning a Ferrari seem as exclusive as having a Ford Focus.

Only 30 were ever made. Thirty! There are more people who've walked on the moon than there are Isdera Imperator 108i owners. And unlike those astronauts, the Isdera owners get to experience something truly remarkable every time they look in their rearview mirror. Because the Isdera Imperator 108i is the only production car in history to feature a periscope as its rearview mirror.

Yes, you read that correctly.

A periscope.

Like a U-boat. Sticking out of the roof.

This wasn't some half-baked idea that made it past quality control by accident. This was a deliberate, engineered feature of a car that already looked like it had been beamed down from another planet. The periscope mirror was there to solve a problem that all low-slung supercars face – terrible rear visibility. Instead of forcing drivers to guess what might be happening behind them, the Isdera's periscope provided a commanding view of whatever the car had just blasted past. To understand how something this wonderfully mad made it to production, we need to look at the man behind it: Eberhard Schulz. Schulz wasn't your typical car designer born into automotive royalty. He was an engineer who built his own concept car called the Erator GTE in 1969 purely to show potential employers what he could do. It worked spectacularly. The rolling résumé landed him a job at Porsche's design department before he moved to a small tuning company called BB Autos.

It was at BB that Schulz embarked on his masterpiece: designing a futuristic Mercedes-Benz concept car. The result was called the Mercedes-Benz CW 311. That "311" wasn't some arbitrary model number – it referred to the car's absurdly low 0.311 drag coefficient, which was remarkable for the era. Mercedes liked it enough to allow their name to be used, but not enough to put it into production themselves. So Schulz did what any self-respecting automotive genius would do – he started his own company and built it himself. Hence, Isdera was born, and the Imperator 108i became reality.

The Imperator wasn't just visually spectacular; it had substance to match its style.

Under that wedge-shaped body lurked a series of increasingly powerful Mercedes-Benz engines. Early cars featured a 5.0-liter V8 producing around 300 horsepower, but by the end of the production run, some were fitted with monstrous 6.0-liter AMG V8s pumping out 390 horsepower. In an age when aerodynamic understanding was still developing, the Imperator was cutting-edge. Its gullwing doors weren't just for show (though, let's be honest, they were absolutely for show) – they were part of a comprehensively thought-out design that included shark-styled inlets above the front wheel arches, a large air intake on the left side, and dual exhaust outlets on the right.

The interior borrowed liberally from the Porsche 928, which is a bit like discovering your bespoke tailored suit has buttons from Savile Row. When you're building just 30 cars over nine years, you can't be expected to fabricate every single component from scratch. Despite its Mercedes heart, the Imperator remained resolutely an Isdera. This was no badge-engineered exercise; it was a genuine supercar with genuine performance. Zero to sixty was dispatched in around 5 seconds, with later AMG-powered versions likely being even quicker. The top speed was a claimed 176 mph – fast enough to make that periscope mirror blur slightly at the edges.

In 1991, the Imperator received a refresh. The most notable change was the reintroduction of pop-up headlights that had been on the original CW311 concept car. Because if there's one thing cooler than a German supercar with a periscope mirror, it's a German supercar with a periscope mirror AND pop-up headlights.

The body also became more rounded, perhaps a concession to the changing design language of the early 1990s when everything was becoming smoother and more organic. The trio of small NACA ducts at the front was consolidated into one large one, presumably to better feed the increasingly hungry AMG engines.

After the Imperator's production run ended, Schulz planned to introduce its successor, the Isdera Commendatore 112i.

This too featured a periscope rearview mirror, proving that Schulz hadn't lost his submarine-inspired design flair. Unfortunately, a global financial crisis meant that just one prototype was built before the company faced bankruptcy. If you're a certain age and spent too much time playing video games in the late 1990s, you might recognize the Commendatore 112i from Need For Speed 2. It was one of those cars that seemed too outlandish to be real, yet there it was, a genuine production-ready supercar with a submarine feature.

Isdera wasn't the only manufacturer to toy with the periscope idea. Early Lamborghini Countach LP400s have the nickname 'Periscopio' for their indented rear roof channel that was supposed to house a periscope for rearward visibility. But Lamborghini chickened out and used a conventional mirror instead, leaving Isdera as the only manufacturer brave enough – or perhaps mad enough – to actually put one into production. Now, in our modern era of digital rearview cameras and blind-spot monitoring systems, the Isdera's periscope seems both outdated and ahead of its time. Tesla's Cybertruck uses a digital rearview mirror because the traditional one offers all the visibility of looking through a mail slot. Perhaps a periscope would have been a better solution – certainly a more characterful one.

The Isdera Imperator 108i remains a testament to what happens when automotive designers are allowed to follow their wildest dreams without committees and focus groups watering everything down.

It's a car that could only exist in a world where practicality was a dirty word and engineering eccentricity was celebrated.

Today, finding an Imperator for sale is about as likely as finding a dinosaur in your garden. They very occasionally come up at specialist auctions, where they command prices that would make even supercar collectors wince. But then again, you're not just buying a car – you're buying the only production vehicle in history that lets you play submarine commander on your daily commute.

And that, in a world of increasingly homogenized supercars, is something worth celebrating.

Even if you do look a bit silly peering through a periscope.