This past summer, the National Highway Traffic Safety administration opened a preliminary investigation into just over 400,000 Jeep Grand Cherokees, after some owners alleged their vehicles would roll away after being shifted into Park. Now, the NHTSA has more than doubled the number of Jeep, Dodge and Chrysler vehicles being investigated. And the agency now blames the problems on a confusing shifter design that doesn't adequately indicate to drivers that they haven't engaged Park.

The Detroit News reports that the NHTSA is conducting an engineering analysis on more than 856,000 Fiat Chrysler vehicles. The agency has received reports of 314 roll-away incidents, involving 121 crashes and 30 injuries, caused when drivers exited a vehicle after they thought they'd shifted into Park. And while the initial investigation treated the issue as a mechanical defect, it's looking more and more like the problem has at least something to do with driver error due to a poorly-designed shifter.

The investigation involves 3.6-liter V6-powered 2014 and 2015 Jeep Grand Cherokees, 2012-2014 Dodge Chargers and 2012-2014 Chrysler 300s—all of which use a push-button console shift lever that looks like a traditional PRNDL shifter. But in operation, the electronic shifter works more like a joystick, returning to its center position once you've selected your gear. There is no gate around the shifter; the lever itself moves through somewhat subtle detents, and the whole range of motion is incredibly short compared to a traditional mechanical shifter, perhaps two or three inches from end to end.

The console shifter on a 2014 Jeep Grand Cherokee. The Dodge Charger and Chrysler 300 models included in the investigation use an identical shifter.

It's worth pointing out that the aforementioned Fiat Chrysler vehicles are not the only ones that use this shifter, called the Monostable and produced by transmission supplier ZF. An Audi A8 we recently drove used an identical shift knob, with the thumb button on the left and a PRNDS gear pattern with no separate button for Park.

In testing, the NHTSA found the electronic gear shifter's operation is "not intuitive" and offers "poor tactile and visual feedback to the driver, increasing the potential for unintended gear selection." In Fiat Chrysler vehicles equipped with this shifter design, opening the driver's door when the car is not in Park triggers a chime and an instrument cluster alert, and the engine cannot be turned off with the car in gear; however, NHTSA says "this function does not protect drivers who intentionally leave the engine running or drivers who do not recognize that the engine continues to run after an attempted shut-off."

So while it may seem silly that drivers could be confused by the operation of an automatic transmission, the reality is that this shifter design operates differently enough to require more concentration than a traditional shifter. Folks who've been driving for years, who are used to the way a mechanical PRNDL shifter operates, probably don't think consciously about the act of shifting—it's the kind of act we've committed to muscle memory years ago.

The NHTSA has upgraded its treatment of this problem in FCA vehicles from an investigation to an "engineering analysis," though no plans for a recall have been announced at this time. FCA went to a different shifter design in model-year 2015 for the Dodge Charger and Chrysler 300, and changed the Jeep Grand Cherokee shifter for 2016. The automaker told The New York Times it is cooperating fully with the investigation.

via Detroit News

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