My '07 SC is driven only on sunny days and dry roads. Should I turn off TRAC, VSC, or both? Is there MPG, system wear, or performance advantage by so doing? According to the owners manual it appears that the TRAC can be turned off separately but the VSC can be turned off only if the TRAC is also turned off.

 

I leave them on all the time. Even in ideal conditions, they can save you during an emergency maneuver. I don't see there being anything to gain by switching them from there default settings (unless you are trying to do a burn-out).