My '07 Aveo5 SVM with the optional provision for installing an a/c (but no actual a/c,) does have one, and the manual shows where and how to change it on page 155. After pulling the glovebox you unscrew the metal bar that goes across, then you can unsnap the filter and pull it out. I've pulled mine to vacuum up elm seeds that got sucked into the ventilation system and ended up rattling around against the filter. Perhaps the ones that don't have the a/c provisions don't have a filter?