Truly novel automotive ideas are rare. If you come up with a great idea, there is a good chance that it has not only been thought of, but there is probably an engineer out there who is sick of going to failure mode meetings about it. If your idea is about a new door design, then that engineer is me.
I wouldn’t call myself a closures expert, but I’ve been part of the ideation and early designs of far too many door ideas. And while they all have their advantages (usually: Neat!) and disadvantages (usually: $$$), I believe that the best possible rear door for almost all vehicles is the sliding van door.
You don’t see them very often because their overwhelming usefulness has made them the go-to door for minivans, utility vans, and other vehicles that are widely considered to be uncool. There’s a stigma; you can’t put a sliding door on a vehicle without it being either a soccer mum minivan or a “free candy” creep van.
Nevertheless, they are the best door. They have a large opening area, they’re not much more expensive than a conventional door, You don’t have to worry about opening it into the bike lane, and your kid can’t swing it open into the side of my car. Win all around.
The Cruise Origin has both a sliding rear and sliding front door. This is the correct door combination for an autonomous shuttle moving people around an airport or whatever. There are challenges for this design because to create the large opening you have to ditch the B Pillar.
That pillar takes most of the load when an oblivious teenager runs a red light and T-bones your car. Without a B pillar, that teenagers Ford Mustang would just drive right through your car, coming out the other side where the teenager would glance up from his phone, totally unaware that he had just killed four people.
You could add the B pillar structure into one or both of the doors, but that’s not ideal because you’d still need to secure the doors to the body when they are closed in a way that allows the door to transmit the load into the body, which is hard with latches. The Cruise Origin may have done this, as the in-door pillars look pretty substantial.
It’s a good solution for an autonomous shuttle where everyone is facing each other, but if you have a forward-facing front seat with a front sliding door, you might as well just put the B pillar in the car. Look where the B pillar is on your vehicle: right where the driver’s seat is. You can’t get in there anyway, so you might as well add some body structure there.
A big drawback of a sliding van door is that you need three tracks that are all mostly parallel. You need these three tracks to be far apart because that is the most efficient way to constrain a plane in three dimensions. You could do it with two, but your structural loads (and cost) go way up. The top and bottom tracks are hidden in the body, one in the roof, and one in the floor. The third is the one you see on the outside.
Designers hate this track. You tell a designer that they have to work around a straight, fixed, exposed track and they stomp their feet like a toddler and say “No! No, no, no, no, no!” But like, more professionally. The front of many vehicles don’t really lend themselves to having this track. There’s a lot of curvature and aerodynamics going on up there and you can’t just throw a track on a sloping fender.
But the track doesn’t need to be totally straight, and front crash safety regulations have pushed the front occupant so far back that there is room for a track with a little bit of design effort. We’re also starting to see a lot of van-like things with geometry that would work with sliding front and rear doors. You don’t have to call it a van door. You don’t even have to call your van a van. VW calls theirs a bus. Canoo’s upcoming vehicle is van-like, and they don’t call it a van. They call it a Canoo, which is not even a land-based vehicle, much less a van.
It’s time to embrace the sliding door. It’s time someone tried it front and back on a passenger vehicle. Maybe we could even see more vehicles like the Peugeot 1007 with one siding door per side. Sliding doors all around.