Retractable Doors

Over the past few years I have talked about different styles of doors including suicide and gullwings. For this article I will discuss retractable doors and I originally wrote this article back in 2010, so it was an interesting task to update it!

The first time I saw this style of door on a production vehicle it was on a BMW Z1 – the first of the Z series from the late 1980s. Only about 8,000 were produced and they were the ancestor of the more common Z3 and Z4 models. On the BMW, the doors drop down into a high sill to give the impression of being door-less like an old Jeep or 1930s sports car. The high sill gave good side impact protection but did look a little odd. The doors were made of thermoplastic to reduce weight and  in effect they were half the size of a normal door.

In the US, a California based company called Jatech LLC created “Disappearing Car Doors” that are retrofitted to mass produced cars. They allegedly took their designs to the Big 3 and got acceptance but not a deal to supply any of them. So they decided to retrofit them to cars so that they are easier to enter and exit. The concept is simple: the door slides down into a protected area underneath the car just like an electric window – using a similar set of buttons to operate them.

The company would take a donor car and then strengthen the floorpan creating an enclosed area for the doors to slide in. This protects the doors when opened so that they don’t get damaged. The pillars would then be modified so that the doors could slide down smoothly with the window automatically lowered as the door moves down so that it is also protected.

The company claimed that the design strengthened the overall car body thus making it safer and easier to access the occupants in the case of an accident – however, the side impact protection was never discussed. One would have to wonder what would happen if the shell was twisted on impact – would the doors actually open? The company claimed that they were hinged at the bottom to facilitate access, however you would have to think that in that instance, the doors would impede access to the occupants.

Back in 2010 when I first wrote about this concept, they were getting plenty of airtime including a youtube video:

However, since then there has been very little from the company and a growing number of articles have been written that suggest that the whole idea might have been a hoax. The pictures I have seen certainly didn’t match the construction the company claimed they were doing – the under floor area aways seems to be the same as normal, which suggests that the photos are of cars with their doors removed!

I suspect that the company did exist and has failed – probably because people liked the idea, yet no one was willing to put down cash to have the conversion done! It looks like they were in business up to about 2012 and their web site is now defunct as well. The only Jatech LLC I found in California was a one man business consulting operation. In reality the Disappearing Car Door company has lived up to its name!

With regards to any retractable door system, I think that it would add significant weight to a vehicle and that would have a corresponding impact on fuel economy, tyre wear and handling. Like the BMW, the doors would need to be made of a lightweight material such as carbon fibre and be strong enough to pass a side impact test.

The other more sensible view is that for the majority of cars, the standard front hinged doors work just fine, so why would you move away from a design that works? Having retractable doors on a show car is a different proposition as it wouldn’t be used regularly on public roads and the buyer would be willing to splash the cash for appearances.

The better option for a manufacturer wanting a different door configuration would be to follow Tesla and use the “falcon wing” doors from the Model X.