Well, as far as gas mileage go, i have never been impressed. Some people have gotten nice results but as for me a full tank of gas never lasted more then 350 kms (around 215-220 miles) no matter how much i babied it or stomped on the gas. And that was when i still had the 1.6L. Keep in mind i have the 1st gen, the new gen has a reworked ecotec engine with better technology, so gas mileage should be better.

As far as reliability goes, i've been pleasantly satisfied, nothing major really happened and everything was covered under warranty, a strong reliable car for the price.

If you want a cheap on gas car you should look at a Toyota Yaris, the gas mileage of those is incredible, but its also almost 5 grand more for the base model then an Aveo base model. Personally i prefer the styling of the Aveo over the Yaris.