The Sonic LT/Premier’s optional lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane. The Rio doesn’t offer a lane departure warning system.
The Sonic’s blind spot mirrors use wide-angle convex mirrors mounted in the corner of each side view mirror to reveal objects that may be in the driver’s blind spots. The Rio doesn’t offer a system to reveal objects in the driver’s blind spots.
The Sonic has standard OnStar®, which uses a global positioning satellite (GPS) receiver and a cellular system to get turn-by-turn driving directions, remotely unlock your doors if you lock your keys in, help track down your vehicle if it’s stolen or send emergency personnel to the scene if any airbags deploy. The Rio doesn’t offer a GPS response system, so if you’re involved in an accident and you’re incapacitated help may not come as quickly.
Both the Sonic and the Rio have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front seatbelt pretensioners, front-wheel drive, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, available collision warning systems and rear parking sensors.
For its top level performance in all IIHS frontal, side, rear impact and roof-crush tests, and with its optional front crash prevention system, the Insurance Institute for Highway Safety grants the Sonic the rating of “Top Pick” for 2016, a rating granted to only 145 vehicles tested by the IIHS. The Rio has not been tested, yet.

