My thoughts on MPG based on owning three T4R's, all similarly modified. The current model is a 17 Pro. MPG is a function of fuel, driving style, vehicle load out, tires, stance, speed and road conditions.
1. Regular or Premium: Data I keep shows premium equals slightly better MPG.
2. Fuel: Winter or Summer Blend makes a difference. Summer Blend equals better MPG
3. Throttle input: Easy-Medium or hard makes a difference in MPG.
4. Geography: Flat, rolling hills, steep hills. enough said here
5. Cruise control: I love the 4Runner, but the most worthless CC in any car owned or driven. It's marginally effective in flat terrain only. Best full MPG obtained by using the right foot and gradual throttle increases anticipating rood conditions noted in point 4.
6. MPG Gauge: Just about as bad as Cruise control. I always compute MPG based on trying to fuel up to same level and use gallons filled to miles driven. Clearly some subjectivity here, but better accuracy then using then equipped gauge.
7. Sprint Controller: Only increases throttle response. Found best MPG obtained keeping it set at sport 2-IMO best compromise.
8. Vehicle loading: How much weight loaded in vehicle.....roof rack only = increased resistance. Load something on the roof and you have substantially increased the resistance on the moving brick. Same applies to towing.
For me boils down to what works best for me = acceptable MPG.
Did I mention I just love the 4Runner????