Lightroom :: D600 RAW Files Look Different That D300 Raw Files?

RAW files from my D300 and my D600 look completely different. These are both NEF files, imported to Lightroom 4.2 using exactly the same import preset. I did NOTHING to either file, except that the D300 one was at 1/160 second and the D600 one was at 1/200 second, so I changed exposure on the D300 one by 1/3 stop so they would match. What I did was to shoot the D300 picture, then carefully changed the lens over to the D600 without moving anything, changed the D600 to DX mode to match the field of view and shot the same picture. The files should be essentially identical.
 
 [b]This is from the D600:[/b]

You will notice that the saturation on the D600 image is much higher. And it's much more yellow. The pictures were shot 2 minutes apart, from the same spot. Same lens, same camera settings.
 
First thing I did was to change the color temperature and tint to match: from  4150/+6 to 4200/+2. There was no visible change (I'm looking at them in compare mode in Lightroom on a calibrated monitor).
 
Next, I tried to change the D600 image to match the D300 one. I had to make substantial changes to both color balance and saturation of various colors, as well as contrast and black levels to get close. I'd give you absolute numbers but it varies from image to image. In this case, I had to drop the color temperature to 3500, for instance. The easiest way to do this was to use the white balance eyedropper on a grey area in the road.
 
I'm wondering if this is related to how LR handles the D600 NEF files. LR 4.2 says the D600 algorithm is 'preliminary'. Could this be part of it?