The Coefficient of drage for the Yaris is .29 which is great for an econo-box.
Sure this car is "plasticy" but I say it is refined because although the materials are not expensive, the car is built tight, no rattles, great fit and trim, and does not vibrate except for a suble vibration when one puts a big load on the engine, which I almost never do for better MPG ;-)
It drives like a car much bigger then it looks. Inside it is very simple, pragmatic, utilitarian, and minimalist in design. Beautiful simplicity.
I drive a 2007 Toyota Yaris Lift-Back, and the sticker price shows EPA City/Highway of 34/39, but after 1,200 miles of using some of the pointers found on this site, I average 44.5 MPG in mixed driving...I never thought I could get better then the EPA estimates...I was astounded, and this with an auto-tranny!
Welcome to the site! Hope you find it as helpful and fun as I do! Great job with the 44.5 MPG! Awesome with an automatic!