Normally, fixing the exposure on this inadvertently underexposed image (inset) would result in at least some noise and/or color shifts. But note how clean the adjusted image still is and how saturated the colors remain.
(1/125 sec, f2.8, ISO 400, AWB, matrix metering, 24-70mm f2.8 lens at 70mm)
This ISO 800 photo looked so clean that I gave up looking for an example of noise artifacts and instead cropped in on the detail available in the image--that's from all the way in the back through the tunnel.
(1/15 sec, f4.5, ISO 800, AWB, matrix metering, 24-70mm f2.8 lens at 24mm)
The D800 has noise at ISO 3200, but its in-camera processing is pretty intelligent. Notice how you can only see the artifacts in the true shadowy areas, but none in the brighter areas. (Download the full 21.4MB image.)
(1/125 sec, f3.5, ISO 3200, AWB, matrix metering, 24-70mm f2.8 lens at 48mm)
This shot registered in the extended ISO range as ISO 10159. The JPEG looked a little mushy because the camera boosted the exposure a bit too much, but with some quick-and-dirty processing, the raw looks pretty good at small sizes.
(1/160 sec, f9, ISO 10159/Hi 0.7, AWB, spot metering, 24-70mm f2.8 lens at 70mm)
The Standard and Neutral color settings are similar enough that I had no qualms about shooting in Standard; the greens are just slightly pushed in Standard. But they're so similar that I might have switched the samples here. I can't tell. Neutral does have the sharpness turned down, however.