The Sonic-based EV will reportedly have a 200 mile range, which will presumably come from the new battery that LG Chem (battery supplier for the Volt) is working on right now. That will arrive in 2016, which suggests that the Sonic EV won’t be introduced until at least that date.
The Sonic EV will also be built in Michigan, which will allow GM to gain regulatory credits for selling a pure EV that is also made in America. The Chevrolet Spark EV, which is built in Korea, is not eligible, and has a range of just 82 miles.