Credit: Jonathan Gitlin

Earlier this week, Ars spent some time driving the new Nissan Leaf. We have to wait until Friday to tell you how that car drives, but among the changes from the previous generation are door handles that retract flush with the bodywork, for the front doors at least. Car designers love them for not ruining the lines of the door with the necessities of real life, but is the benefit from drag reduction worth the safety risk?

That question is in even sharper relief this morning. Bloomberg's Dana Hull has a deeply reported article that looks at the problem of Tesla's door handles, which fail when the cars lose power.

The electric vehicle manufacturer chose not to use conventional door locks in its cars, preferring to use IP-based electronic controls. While the front seat occupants have always had a physical latch that can open the door, it took some years for the automaker to add emergency releases for the rear doors, and even now that it has, many rear-seat Tesla passengers will be unaware of where to find or how to operate the emergency release.

A power failure also affects first responders' ability to rescue occupants, and Hull's article details a number of tragic fatal crashes where the occupants of a crashed Tesla were unable to escape the smoke and flames of their burning cars.

China to the rescue?

In fact, the styling feature might be on borrowed time. It seems that Chinese authorities have been concerned about retractable door handles for some time now and are reportedly close to banning them from 2027. Flush-fit door handles fail far more often during side impacts than regular handles, delaying egress or rescue time after a crash. During heavy rain, flush-fit door handles have short-circuited, trapping people in their cars. Chinese consumers have even reported an increase in finger injuries as they get trapped or pinched.

That's plenty of safety risk, but what about the benefit to vehicle efficiency? As it turns out, it doesn't actually help that much. Adding flush door handles cuts the drag coefficient (Cd) by around 0.01. You really need to know a car's frontal area as well as its Cd, but this equates to perhaps a little more than a mile of EPA range, perhaps two under Europe's Worldwide Harmonised Light vehicles Test Procedure.

If automakers were that serious about drag reduction, we'd see many more EVs riding on smaller wheels. The rotation of the wheels and tires is one of the greatest contributors to drag, yet the stylists' love of huge wheels means most EVs you'll find on the front lot of a dealership will struggle to match their official efficiency numbers (not to mention suffering from a worse ride).

China's importance to the global EV market means that, if it follows through on this ban, we can expect to see many fewer cars arrive with flush door handles in the future.