John Jordan sent this tip for the adaptive grid, which he uses with AutoCAD 2007. "Change the setvar GRIDDISPLAY according to how you want the grid to display. I set GRIDDISPLAY to 0 so that it will only show the limits of the drawing. The setting is stored as a bitcode using the sum of the following values:

    0 – Restricts the grid to the area specified by the Limits command.
    1 – Does not restrict the grid to the area specified by the Limits command.
    2 – Turns on adaptive grid display, which limits the density of the grid when zoomed out.
    3 – Initial setting.
    4 – If the grid is set to adaptive display and when zoomed in, generates additional, more closely spaced grid lines in the same proportion as the intervals of the major grid lines.
    8 – Changes the grid plane to follow the xy plane of the dynamic UCS.

"Note: Setting 4 is ignored unless setting 2 is specified."

NOTES FROM CADALYST TIP PATROL: This tip works as stated and is explained in the AutoCAD Help file under GRIDDISPLAY. As the HELP entry (and the tip) note, if the GRIDDISPLAY setvar is not (initially) set to 2, then the adapative 4 setting cannot be applied. Not included in this tip, the AutoCAD HELP entry also references the VSCURRENT settings, which will let the user adjust the color and style of the GRID.