Heavy fuel usage/high revs

[WeeYari]

3000 rpm at 110kph is right on par. Keep in mind that the bigger the engine displacement, the lower it will rev. The Camry with the larger engine will naturally rev lower. At highway speeds, a V8 will be sub 2000rpm.
When it comes to efficiency, 6 to 6.5 l/100km can realistically only be achieved under optimal driving conditions. For the average Joe, this would be cruising on open highway at a steady 80 kph. No stops, starts or changes in acceleration.