The greater the displacement, the more fuel consumption.

Your logic is correct, but it only exists at the theoretical level.

This requires engine technology. For example, Mercedes-Benz E200 and E300, the fuel consumption of E200 is higher than that of E300, because the power of 200 can't pull E-class.

To put it simply, it is more labor-saving for children to push the table with the strength of sucking milk than for adults to gently push the table. So the large displacement depends on the weight of the car.

Now what wind resistance, tire size and so on will affect fuel consumption. Many car companies are looking for a balance between fuel consumption and power.

At present, the most fuel-efficient technologies are stratified combustion and supercharging technology. Volkswagen has done a good job, and Lexus's hybrid power is also good.