Yes, the size of a car or motorcycle engine can have an impact on fuel consumption, although it is not the sole determining factor. Generally, larger engines tend to consume more fuel than smaller engines. This is because larger engines have a higher displacement and typically require more fuel to produce the power necessary to move the vehicle.
Other factors include the vehicle's weight, aerodynamics, transmission type, driving style, road conditions, and overall vehicle efficiency. Modern advancements in technology have also led to the development of more fuel-efficient engines, irrespective of their size.
Additionally, different engine designs and technologies can have varying levels of efficiency. For example, a smaller engine with advanced turbocharging and direct fuel injection might be more fuel-efficient than a larger engine with an outdated design. Therefore, while engine size can provide a general indication of fuel consumption, it's not the sole determining factor, and other variables play a significant role as well.