The 2014 Kia Rio has an interior that's a little tighter on space than other models in its subcompact class; but pleasing trims and materials and reasonably good cabin refinement keep it more cheerful than the typical cost-conscious hatchback or sedan.
The Rio has a more sloped roofline, which puts it just behind the related Hyundai Accent in official interior space. If you want to make more of cargo versatility, the Honda Fit is still a far better pick, but compared to most other small-car picks, it's a competitive package.
By the numbers, the Rio sports a 101.2-inch wheelbase, has an overall length of about 160 inches, and offers up a cargo area of 15 cubic feet (or 13.7 cubic feet, for trunked sedan models). It's significantly larger than the previous model.
None of the fundamentals are missing. Good front seats, with relatively long bottom cushions cushions for the class and long seat travel should help bring enough comfort for the commute. The sporty Rio SX models get more seat bolstering--and it's mild enough here where no one's really going to object to the addition.
In back, it's definitely more confining than in the Honda Fit, or even the Versa Note; with the front seats near the back of their travel (for an average-to-taller driver) you won't have any rear knee or foot space to space in back; and headroom is on the tight side.
Cargo space is also no better than you'd expect for a subcompact--although big-box boxes and travel bags do fit nicely within the squared-off hold, whether we're talking about the hatch or the sedan.