Eccentric Doors - Your Guide to The Difference Between Butterfly And Dihedral

Fisker EMotion 9 photos
Photo: Fisker
Lamborghini Aventador - scissor doorsSpyker D8 Concept - rear-hinged doors for the rear occupantsMcLaren P1 - butterfly doorsMercedes-Benz SLS AMG Black Series - gullwing doorsAston Martin DBX Concept - swan doorsLamborghini Murcielago exhibiting a texbook set of "scissor" doorsFalcon doors on Tesla Model X - note the dual hinged-doorsKoenigsegg Regera and its unique dihedral synchro-helix doors
The automotive industry has blessed us with many eccentric creations, and doors are among them.
These days, you can get as much as six types of doors that open differently than what you might find on the average Joe’s car. We review them to clarify the difference between a scissor door and a gull-wing one, among other things. Evidently, there’s no need to discuss the standard design that you find on most cars on the market.

Instead, we talk about those used that you might find in supercars and hypercars, with a few exceptions. Every once in awhile, a company comes along and introduces an unusual design in a volume model, but these are exceptions. Sliding doors have not been included in this list because they are not that uncommon these days.

Dihedral doors

Koenigsegg Regera and its unique dihedral synchro\-helix doors
Photo: Koenigsegg
This is one of the most recent designs in the world of car doors, and the name comes from geometry. We are not going to take the time to explain what Dihedral means, because we want to focus on doors in this story, and not on the years of work required by teams of talented engineers to design those parts.

In short, dihedral doors are found in the Koenigsegg range. A door that can be considered dihedral will open to the side, and then upwards and at an angle. It is worth noting that they also have hinges on the A-pillars, which help support the entire device.

Koenigsegg's creation has provided us with a set of doors that are as innovative as the scissor doors of the Lamborghini Countach in their day. The main idea with Koenigsegg’s dihedral synchro-helix system is never to park too close to a high curb, or a big bill for carbon fiber repairs will be handed to you at the dealership.

Scissor doors

Lamborghini Aventador \- scissor doors
Photo: Lamborghini
These are already classics, as the first units were launched with the Countach back in the 1970s. The Italian supercar manufacturer kept making them, and they eventually became known as “Lambo doors.” Evidently, Lamborghini is not the only automaker that uses this system, but it is renowned for them.

It is slightly redundant to note, but Lamborghini does not employ them on every model. However, a quick look at the Aventador will show you that the model has a system that takes the doors slightly outward at an angle, but they still count as “scissor” doors.

These doors have a major flaw - because they are opened vertically, you will have clearance issues in parking garages with low ceilings. In some occurrences, you might not be able to exit the vehicle, or you will not be able to do it without a person handling the door while you crawl out of the car like Leo DiCaprio in The Wolf of Wall Street.

Many aftermarket companies have offered kits that turn a regular door into a “Lambo door,” but no system matches the originals. Evidently, the lighter doors of the Italian supercar are easier to open than those of a second-hand hot hatch that has been “tuned” with cheap parts.

“Suicide” doors

Spyker D8 Concept \- rear\-hinged doors for the rear occupants
Photo: Spyker
This type of door is no longer common, but it used to be popular many decades ago. The term is only employed in slang, as manufacturers prefer to call them “rear-hinged doors,” or “coach doors.” Manufacturers like Mazda, Saturn, and Opel/Vauxhall have offered them on affordable models, but all of them focused on improving access to the rear seats.

Rolls-Royce is one of the few brands that still employs rear-hinged doors, and the Phantom Drophead Coupe was one of the few contemporary models that had this system for the driver’s door. The Phantom Series II also had this setup for the rear occupants, which is expected to be carried over to the next generation.

We must note that the ones offered on the Mazda RX-8, Opel/Vauxhall Meriva, and Saturn SC/Ion needed the front door to be opened to allow the rear-hinged doors for the rear occupants to be opened. In most cases, these doors are very helpful to the rear occupants, because they get better access to the rear seats, which is especially useful when you have to fit a kid into a child seat, for example.

Butterfly doors

McLaren P1 \- butterfly doors
Photo: McLaren
The butterfly system is similar to the scissor solution, but it brings an angle in the game. These doors are opened upwards and towards the windshield to allow easier access inside. With time, they have become more popular than scissor doors because of that practical note regarding access.

Unfortunately, this solution is worse than “scissor doors” when it comes to access in cramped spaces or garages with low ceilings, but not on all models. If you can get away with exiting or entering a car with scissor doors in a packed parking space (on the sides of the vehicle), the same does not apply to butterfly doors, which need more lateral room.

The most notable cars with this system are the Mclaren F1, McLaren P1, Ferrari Enzo, Mercedes-Benz SLR McLaren, Ferrari LaFerrari, BMW i8, and much more.

Gull-wing and Falcon doors

Mercedes\-Benz SLS AMG Black Series \- gullwing doors
Photo: Mercedes-Benz
Gull-wing doors and Falcon doors are surprisingly similar, and that is why they are placed together. Both of these systems are hinged to the roof of a vehicle, but the way that they are opened will make a difference between a “Falcon” and a gullwing.

The idea is that both of these doors are opened horizontally and require much room above the vehicle, but the Falcon units have a moving roof panel that helps reduce that requirement.

The most famous application of a falcon door these days is on the rear doors of the Tesla Model X, which involves moving a roof panel to allow opening them in a garage with less clearance.

Meanwhile, Mercedes-Benz holds the title for the most known gull-wing application, which was a technical necessity for the W198 300SL of the 1950s and early 1960s.

At that time, the 300 SL had an aluminum tube space-frame chassis that enveloped the passenger compartment, which led to the introduction of the gull-wing doors as a necessity, not a fashion statement. However, those doors did become a statement shortly after its introduction.

Swan doors

Aston Martin DBX Concept \- swan doors
Photo: Aston Martin
This type of door looks like a regular one, as it opens to the side. However, they are employed in models with a small ground clearance to prevent scrapes. Aston Martin is a big fan of this system, as it was used on the DB9, DB10, DBS V12, DBX, One-77, Rapid, Vantage, Vanquish, Virage, and the CC100 Speedster.

Other automakers have employed them for the same reasons. Other examples are the Lagonda Taraf, Pagani Huayra Roadster, Chevrolet Corvette Stingray, and Hennessey Venom GT.

The “swan” doors are an excellent illustration of practicality from supercar makers, as they have imagined the fact that people will drive their creations on public roads. Even the wealthiest of customers do not want to take their cars to the shop to fix door dings, so swan doors were designed to prevent that from happening.
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About the author: Sebastian Toma
Sebastian Toma profile photo

Sebastian's love for cars began at a young age. Little did he know that a career would emerge from this passion (and that it would not, sadly, involve being a professional racecar driver). In over fourteen years, he got behind the wheel of several hundred vehicles and in the offices of the most important car publications in his homeland.
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