I can guarantee you that they are doing exhaustive usability testing. I've had friends that worked in Ford's design and usability group. EVERYTHING is extensively demo'ed and discussed to death. My friends in the design group complained that the actual engineers would take their designs and fight them constantly on every change and that what WAS a nice interface was junk by the time it went into the vehicle.
I suspect that the engineers fighting them is really just a case of the hardware team and the software team not understanding the world the other lives in. The hardware team is working with a slow as molasses processor that is the only thing thats been approved for the ridiculously rugged life that a car CPU lives and the software people don't understand that just because a webkit rendering engine is completely fluid on their 6 month old Precision workstation it won't be on a 500mhz in dash processor.
* The one and only physical button car took 10 seconds total to complete their tasks
* Two touch-screen cars (Volvo C40 and Dacia Sandero) took only 13 seconds to complete the tasks
* Most touch-screen cars take 20-40 seconds
These results are certainly consistent with the hypothesis, "A moderately well-designed physical interface is likely to be better than an extremely well-designed touch-screen interface". But it's not really enough data to support the hypothesis that all physical interfaces are better than all touch-screen interfaces. You'd want to see what the curve looks like -- with it so close, it's quite possible that some, or even many, physical interfaces would take longer than 13 seconds for their benchmark.
And if you slow people down by 30% but reduce costs by a significant fraction, I think that's probably worth it.
More likely they are doing testing but aren't measuring the right things or are performing the tests improperly. I can say with high confidence that any of today's UX folks don't understand the scientific method nor statistics.
Or they know what they're doing, hate it but decide for it anyway due to some sort of FOMO (the competition does it also!) Maybe it's comparable to the glossy laptop screen fad some years ago.
I suspect that the engineers fighting them is really just a case of the hardware team and the software team not understanding the world the other lives in. The hardware team is working with a slow as molasses processor that is the only thing thats been approved for the ridiculously rugged life that a car CPU lives and the software people don't understand that just because a webkit rendering engine is completely fluid on their 6 month old Precision workstation it won't be on a 500mhz in dash processor.