For example, this chart on the Tupolev 154 shows the effect. As the load factor climbs to 100% the fuel used per passenger drops.
This is a basic and fundamental way to save on gas. We must look to modify the way we get around such as to keep vehicles running at close to full capacity. Do that and we will all save on gas.
|Load Factor (%)||Passengers||Fuel Burned per Passenger-km (kg)|