Fuel economy competitive with earlier generations despite more power.
Stock 2013-2018 6.7 baseline:
- Highway (conservative): 16-20 MPG
- Mixed driving: 14-17 MPG
- Towing 15k lbs: 10-13 MPG
- Emissions delete: Improves 2-4 MPG (no regen burning fuel)
Mild mods (turbo, tune, 550 HP):
- Highway: 14-18 MPG (deleted), 13-16 MPG (emissions)
- Mixed: 12-15 MPG
- Towing: 10-13 MPG
Moderate builds (700 HP, injectors):
- Highway: 12-16 MPG
- Mixed: 10-13 MPG
- Towing: 8-11 MPG
High-performance (850+ HP, compounds):
- Highway: 10-13 MPG
- Mixed: 9-11 MPG
- Towing: 7-10 MPG
Factors affecting fuel economy:
- Emissions equipment: DPF regen biggest fuel economy killer; delete helps significantly
- Driving style: Massive torque tempts heavy throttle use
- Tuning: Aggressive tunes prioritize power over economy
- Injector size: Bigger injectors make fuel more accessible
- Weight/aero: Heavy trucks with lifts and big tires suffer
Aisin vs 68RFE economy: Aisin typically 1-2 MPG better due to more efficient gear ratios and smoother lockup strategy.