New Owner in AZ

Greetings, I'm a new Aveo owner from Arizona. I rolled the dice on this one and hope it pays out. I got a 2011 automatic with 21,600 miles on it for $9,000. Face value seems like a fantastic deal, but it was a rental that Hertz is selling. They had a few days where the Aveos were offered with huge discounts and I actually found this to be the best one despite it being located at the Los Angeles airport. So, I used a buddy pass to fly for free, picked it up and drove it back to Phoenix.
I got it all the way to Arizona before buying gas, needed only half a tank, and I got 38.52 mpg! And that is with driving faster than normal, averaging 70-80.
I have been a long time truck and SUV owner and have recently been faced with a 100 mile per day commute. Even with an intake/exhaust plus cruise control locked into 65, I was maxing 17mpg. Oh, and that's buying 89 octane gas. My engine (2007 Hemi) was tuned specifically for 89 octane and I did actually notice about a 15% decrease in fuel economy when using 87 octane.
I realize I probably could have purchased a more fuel efficient vehicle for the money, albeit with more miles or older, but I am familiar with the Aveo since my sister has a 2010 and I like the car. Because I will be using this only as a commuter, I will be interested in maxing out my fuel economy. I know the top techniques are proper tire pressure and laying off the gas when appropriate, but maybe I'll try an ultra-gauge and K&N down the road.
The whole buying a rental car thing is new to me, and despite talking to numerous people who had positive experiences, I feel I'm still rolling the dice a bit.
I'm glad to be here and will be jumping in all the forums to get some good info!

Welcome to the forum! Seems like you got a good car, and some good MPG's :)

Driving 55 MPH will help your MPG's, but you are already doing really good.

Welcome to the site.

The Aveo is a fine vehicle as long as you keep up with regular maintenance. Its when you completely ignore/abuse it that it starts to become an issue. Sadly, being such a low priced vehicle this is a common occurance by many owners. Thats how I nabbed mine super cheap from a girl who let the timing belt snap!

Yeah, filling the tires up (a bit higher than the factory spec helps more) is a good thing for mileage. I run mine at max sidewall pressure on the tire. The ultra gauge will definitely be a good addition.

I wouldn't bother with the K&N unless you're looking for a little more power. Filters are sized for peak engine power, and unless you're really mashing the pedal a lot its not going to be a restriction at lower power outputs (thus the stock one isn't hurting mileage).

Welcome to the forums! Glad you joined us!