Why are cars with big engines a problem?

Why are cars with big engines a problem?
As the Engine capacity/size increases it is unavoidable that the rest of the engine has to increase in size to cope with the larger forces the larger engine capacity produces.

This has the unavoidable effect of increasing friction, and reducing Fuel Efficiency.

Hence a 4 liter engine will use more fuel than a 2 liter engine if all other things such as:
Technology, weight of vehicle, driving style, fuel type etc are the same.

Having a vehicle capable of 180MPH, that does 15MPG is regarded as "a problem" by some when the speed limit is 55MPH and a vehicle capable of 100MPH will do 60MPG.

**Cars with big engines are considered a problem because it uses more fuel and creates bigger emissions.