I own a '14 Mirage ES with navigation. On a recent trip to California I rented a '14 Kia Rio for 2 weeks.
Here is my comparison of the 2 vehicles:
The Kia had far fewer features than my Mirage. No keyless entry or push button start. Boy do you get used to these features quickly when you have them. I felt like I spent most of the two weeks getting the keys in and out of my pocket.
The A/C on the Rio did a great job of keeping the interior cool, but it was manual. I never realized how adjusting the fan speed becomes a pain, but it does. The automatic A/C on the Mirage is more appreciated now.
No back-up camera or nav on the Rio I had. I know these are available at the top trim levels, but the price of these options puts the Rio at much more than the Mirage.
Power windows and locks were just like the Mirage and worked the same. Both cars have an auto down feature for the driver's side window.
The Rio had a 4 cylinder and did have more pick-up. Engine was quieter when getting up to speed. Gas mileage wasn't so good. In combination driving (1/2 freeway, 1/2 city streets) the computer's MPG readout never got above 25 MPG.
Rear visibility on the Rio was what I would consider poor. The rear window has wide pillars at the corners and the window itself angles in towards the top. This makes for a fairly small view out the back. Really missed my back-up camera from the Mirage. I noticed when I got home that the rear window of the Mirage is more of a rectangle which gives you a much better view out the back of the vehicle.
The Kia's tires were broader than the Mirage's. I didn't find any difference in handling or braking. Both cars seem to handle fine.
One area I did find a big difference was in the turning radius. The Mirage turns on a dime and will fit into any available parking space - even those oriented the opposite way. The Kia is not very good in this respect. More room needed for turns.
The front seating positions in the Rio were comfortable. There was plenty of room for both driver and passenger. Pretty comparable to the Mirage.
Materials were plain but the fit of the panels was good and the controls were organized in a logical way. I personally think the Mirage has a better looking interior, but both cars seem pretty evenly matched in this area.
The Rio and the Mirage are about the same cargo wise. We had no trouble fitting suitcases and normal shopping items in the Rio. Same for our Mirage when we have needed to carry something in the back.
One thing the Mirage has been criticized for in various reviews is the one string connection between the cargo cover and the rear hatch. Reviewers seem to point this out a a sign of the Mirage's cheapness. Well, the Rio had the same one string connection and it worked just fine! The cover's weight is in the ounces and the one string seems to do the job on both cars. Just funny that I have never noticed this being mentioned on Rio reviews.
The front end of both cars differs, but the rest of the car is about the same. Personally, I prefer the front end styling of the Mirage. The Rio has the same grill design as the Optima and the other Kia cars. It looks fine but it is very familiar.
Bottom line is that I wouldn't trade my Mirage for a Rio if the cost and feature set was the same. Driving the Rio made me feel that I had good solid basic transportation. The Mirage, to me, is a fun driving experience.
I'll take the lower price, extra features, and better MPG any day.