I know it isn't one of your two choices, but I recently (3 months ago) bought a 2013 Prius C (bought new from dealer, I know not a very mustachian thing to do). I paid $17,300, as it was an 'old' model. Assuming you could still find a 2013, I think you could find a similar deal. The C variant of the Prius is a bit smaller, it has a 1.5l vs the 1.8 in the regular prius. I have hand calculated my mpg every tank for the past 5,000 miles, the total average is 61.3. The best has been 64, and the worst, 57.5. Also, with a new vehicle you have the added benefit of a longer warranty, and knowing that some jackass didn't forget to change the oil.