Starting in 2009 they went to different engine:
1.6L Ecotec engine with variable valve timing and 106 hp (79 kW) standard on all models
It had a 100,000 mile timing belt and some other stuff that made even more fuel efficient. Of course that get eaten by the extra weight of extra features.
Chevrolet Pressroom - United States - Aveo and Aveo 5
The previous model used a variation of the ETEC engines that had fixed timing and the 60,000 mile timing belt. Many victims have fallen to that belt.