D90 review - max DR @ ISO400
there are curves that make the Jpeg from a RAW file, which happens inside the camera. There is nothing wrong with D90, but it has dreadful curves in camera. Similar to the D700. As seen later in the review the RAW file has at least 1 or 1+1/2 stop Highlight headroom. With shooting RAW or applying a custom curve in the camera the DR of the D700 went up by 1 stop. The same can be done in D90. Also in the D80 the DR with Custom curves improved by 1/3 shadow and 1+1/4 stop highlight. So that has nothing to do with the camera.
It can be fixed by custom curves.
It can be fixed by firmware, but Nikon cannot be bothered.
It can be fixed with RAW and Highlight protection set to at least 40.