when the Torq Converter is not locked you have about 10% loss of Power. If you have the t/c lock up while accelerating you get a little boost of power when it locks. Im not really sure how much this saves fuel wise but it certainly brings me to 60mph faster then when it doesn't lock.
2008 Ford Focus SE, ABS w/ T/C, 4 Door, Auto. 58,000 miles Purchased 05/08 with 200 miles (DD now, old baby hauler)
2013 Ford Escape 1.6 EcoBoost My Touch (Baby Hauler)