"emissions" is more than just out the tail pipe..

US cars are often detuned to use a little less gas per pedal position than the rest of the world. It is also typical that tuning for different octanes offered, types of driver (aveo is a "big" car in some countries where it is a starter little econo box here), and reliability (some manufacturers detune engines to have less recall work).

But if you look at global cars and can fine the ones with the same engines, historically european etc cars with the same engines offer a few more hp.. one reason why bmw, JDM, vw, mercedes, etc all have homeland engine swap as a desirable commodity here.