It's a good question. For me, the more interesting question is not "is it ethical," but "will they open the data for any reason." The ethical question is difficult to answer because you cannot control how others use this data - safety is certainly the end goal, but used improperly, it could harm more than help.
Regardless of the ethics, how valuable is the data to other manufacturers? Assuming they have the same sensor suite, it's likely to have some value. The vehicle controls, shape, response, etc would need to be tweaked, and the sensor locations will obviously make things a bit more complicated. My guess is that it has a lot more proprietary value than open value. And when BMW, Mercedes, etc., get their sensors sending feedback to their HQ, it'll take no longer than a few days before they're up to speed. Their scope and production numbers are that much larger.