Great job. The Aveo rates at around 28 mpg, so 40 is a 43% gain.
Losing all the weight, no doubt, reduced the fuel used to get up to speed.
A little bit of over inflation of the tires, if you're comfortable with that will give you a boost.
A grill block and smooth wheel covers are great projects that will get you some gains as well.
Keep it up!
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