Went to the IIHS web site to look at all those "Good" crash test ratings, the site included the weight of the "LT 4-door". So it looks like "2800 pounds" is a good round number.
TESTED VEHICLE SPECIFICATIONS:
2012 Chevrolet Sonic LT 4-door
Class: Small car
Weight: 2,798 lbs.
Side airbags...