Maybe not entirely free at highest rpm, but if you think of quicker throttle response, for instance, and part throttle torque, also.

I usually drive my Firebird (6.3 Liters v8-500-520HP+) and at average it drives 5.5-6 Kilometers per Liter.

Sometimes I drive my '2000 Nissan Pathfinder (3.3 Liters v6 -around 230-250HP), and it drives 5-6.5 Kilometers per Liter.

Keep in mind that both are automatics, and at 60 mph. they are both around 2000 rpm's.

That's fuel effiency. -Free horsepower

So even if the 2000 Nissan has EFI,- the lack of headers, the bad exhaust system (y type), the presence of CAT, and possibly bad head/combustion chamber flow, -it has very poor effiency.