DSTC can be turned off but not fully.. it will turn the low speed wheel spin function off. RSC (roll stability control) is constantly on even with DSTC button in off position. But if u have ABS, DSTC fault in system (traction light comes on and stay on) all traction control function will be disabled. And yes turning off DSTC does not gain or loose any fuel economy.
Not trying to prove anything just want to ask other for opinions (Since I don't know everything)
Current car: 2002 Volvo V70 T-5
Previous car owned:
2000 Subaru Legacy GT Wagon (WRX conversion)
1996 Acura 3.2TL