That Chevy could use if they ever made a Sonic SS/Z-Spec.

Trying to think of an engine in GM's US engine stable

The 2.0T is too powerful for the Sonic. (250HP, that's Focus ST levels of power.)

Uprated 1.4T? Eh, I doubt that could make 200 HP without having to do a lot of work.

They could go the NA route and shoehorn their 2.5L Ecotec in there, but that would probably be really big for the engine bay. If it would even fit at all.

They really don't have an engine right now that could be used. It wouldn't make financial sense to make a unique unit. I mean, it's not like the Fiesta ST's engine is a unique, it's out of the Fusion.