The Genesis GV90’s 155-Pound Coach Doors Are an Engineering Flex

Rear-swinging coach doors—also called suicide doors—have never gone out of style but they have become increasingly rare on modern automobiles. Only regularly seen on Rolls-Royce models, coach doors are hard to engineer because they’re both difficult to seal from weather and often functionally compromised for safety’s sake.

Rolls-Royce’s coach doors, for instance, reveal a physical B-pillar that runs from the roof to the floor of the car. This increases rigidity and it’s great for safety, but those pillars can hinder graceful ingress and egress—one of the key reasons automotive designers dream of coach doors in the first place. Other automakers, like Honda on its 2003-2011 Element or Mazda on the 2003-2012 RX-8, featured B-pillar-less coach doors, but these were stubby and shortened to reduce the body opening and improve crash safety, and could only be opened if the front doors were open.

How has Genesis managed to solve for a lack of a fixed B-pillar, provide proper safety, and deliver freedom of movement with the coach doors on the 2028 Genesis GV90’s Neolun version? According to its designers and engineers, clever structural enhancements and two really beefy hinges are the keys.

How Did They Engineer the Coach Doors?

The coach doors—which Genesis dubs the “Neolun Arch Doors”—almost didn’t happen. Luc Donkerwolke, Genesis’ president and chief creative officer, told us that getting a sign off on the idea from the Hyundai Motor Group president at the time was incredibly difficult. He was told that the Genesis design team would only get the OK if it could develop a coach door version of the GV90 that was as safe—if not safer—than the conventional swing door variant. Donckerwolke told us this was a daunting challenge but credits a talented team of designers who won’t tell him no to getting the job done.

Are the Coach Doors Safe?

Once tentatively approved, Genesis’ first problem was ensuring the GV90 Neolun’s structural stability and safety matched the conventional swing door version without compromising on the vision of a pillarless opening. To tackle that, Genesis’ designers and engineers opted to effectively move the B-pillar structure from the car’s body into the doors themselves.

The GV90 Neolun’s doors feature beefy dual-steel beams rated for 1.8 gigapascals (a unit representing tensile strength; most automotive steel is rated at less than 1.0 GPa). These run vertically along the door’s inside edges and then horizontally along the bottom of the door to where the doors meet the A and C pillars. Additionally, the doors feature heavy duty stoppers mounted on the roof and in the GV90’s door sill to secure the doors to the body.

Genesis also sought to stiffen and strengthen the GV90’s base body structure with what it calls a “hidden roll cage,” consisting of 1.5 GPa steel tubes running through the SUV’s roofline, with additional support coming in the form of high strength steel through the rockers and around the wheel arches, horizontal members spanning the floor of the vehicle, structural foam throughout, and high pressure die-cast aluminum around the rear door hinges.

Lastly, to ensure occupant safety, Genesis also moves the seatbelts from the B-pillar (where they’re found on swing door GV90s) to the front seats themselves, and loads the car with multistage airbags, including what the company says is the world’s first roof airbag.

The GV90 Neolun’s Special Hinges

Circling back to the rear door hinges, the amount of engineering Genesis did to ensure that each 155-pound rear door could be opened smoothly and independently is impressive.

Genesis came up with a “dual-motion hinge” design to solve the problem. Mounted in that cast aluminum panel, the hinge consists of a high strength cast iron “center block” mounted in an aluminum housing.

When the electric opening and closing door is actuated via a button on the door, within the second-row infotainment system, or from the driver’s seat, the door first extends out like a minivan door, and then swings smoothly open about 80 degrees, the hinge sliding along two rails loaded with more than 500 ball bearings, almost like how a forklift arm would work if it were sideways. Genesis says these rails have varying thickness depending on the load bearing path of the door, saving some weight and providing for smooth operation and long-term reliability.

Like other luxury vehicles with automatic opening and closing doors, such as the Cadillac Escalade IQ, the final piece of the puzzle are ultrasonic sensors mounted
in the door. These can sense when an object is in the door’s path and stop travel. Sensors on the inside similarly detect when a person’s body or limbs might be in the way of the door’s travel. Three layers of weather stripping seal the cabin from dust, weather, and noise.

While only the National Highway Traffic Safety Administration (NHTSA) and Insurance Institute for Highway Safety (IIHS) testing will be able to independently verify Genesis’ claims regarding the GV90 Neolun’s safety, we’re hoping that in creating the first functionally pillarless independent coach-door-equipped vehicle since the 1964 Facel Vega Excellence, Genesis has dared other automakers to dream just as big as it has.