What you said is true. But larger CC cars also idle using more fuel than a smaller CC one. So during a traffic jam they wouldn’t fare as well.That is a common misconception. Cars with bigger CC usually have more torque and can be geared lower hence having lower shift points and cruising rpm. I was on holiday in australia in March this year, and we rented a 2010 Ford falcon with a 4000cc inline 6.
at 110 kmh speed limit, the rpm was 1800. I was impressed with the fuel economy of that car, and this experience forever changed my perception of large cc cars.