More than anything it’s important to get the right Make, Model, and Model Year as well as make sure it has an impeccable service history especially engine oil changes and transmission fluid changes.  As an example I would not take a low mileage Hyundai or Kia product or 2012-2014 Toyota Camry.

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Also, don’t be fooled by Kia’s warranty.  They don’t stand behind their product and I have known many family members and co-workers who previously bought a Hyundai/Kia product and the warranty was not honored.  They found a way to deny coverage.  Also, in many cases they said the issue the owner was experiencing was “normal” - total BS.

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Avoid Hyundai Motor Group products at all costs.  If the Corolla or Civic was well taken care of and the right model year and powertrain options, a 100,000 mile one can last far longer than a brand new Kia.

See this site's extensive Hyundai/Kia topic - you be the judge:

https://carkiller.com/scottykilmer/qa/hmg/

Kia Rio (...) $20k out the door

That's way too much! That's like $5k more than the most anyone would ever pay for one.

The issue is that the Rio's US market powertrain is not recommended - the iVT's trash.

For that kind of money, for $22,795 MSRP with delivery - you can get a Toyota Corolla LE.

And that 2.0L DynamicForce launch gear CVT is much better.

a kid a new car

Active safety is a big plus on new cars.

75% of what I can buy a new one for that has a warranty on the powertrain to 100,000 miles?

Add a bit more and get a Corolla LE.

You can get some older American cars for a fraction of the price of a Hondas & Toyotas, and still get decent quality. Some older Buicks were built like absolute tanks. But you have to know what you're looking for. Ultimately the right Civic or Corolla would be best for longevity, however a Lesbre or crown vic will run for a long time too with the right care. 

Any car with 100K has to be checked out thoroughly by a mechanic. Research the model year. Like every one else Honda has had bad years for engines and transmissions. For her 1st car I would by used and cheap. Every new driver has to wreck at least one car before they actually know how to drive. Then talk about spending $15000. I nicknamed my niece "CRASH" after she wrecked her first car. Only took 2 months.

The problem I have had with Kia are the dealers have not been around very long. The sales and repair staffs are immature and pushy. They share Hyundai drive trains which are fare. Hyundai dealers have been around longer and are better established. I recommend a Hyundai Accent over a Rio for that reason. The cars are same but you will be dealing with a more mature salesman who won't be pressuring you to close the deal "This minute!" and the mechanics will know what they are doing. I am not quite sure why Hyundai insists on keeping Kia dealers separate from Hyundai dealers. I have two Kias but I maintain them my self. For the money Kia is OK but for your average person who depends on the dealer for service they can be a real headache.

For those with differing opinions by all means chime in.

I know it’s very alluring. Why buy a used high mileage car when a new one is just a little bit more, and it’s brand spanking new!?

Suffice it to say, there are some used cars that are projected to be great, and others that projected to be destined to quickly become money pits.

The same can be said for a new cars too. Some are great and some a destined to become money pits.

Kia/Hyuandai does intrigue me, because they claim a 100K warranty. But the stories I hear seem to support them trying to get out of the warranty for the most part.

On the other hand, I know Toyota only provides a 36K mile, 2 year warranty, but just from stories, they seem to have your back on major things up to 100K - 150K miles and 8-10 years. This is all anecdotal, so take it for what it is worth.

I recommend researching the specific used Toyota vehicle, and its maintenance history, and have it checked out. More likely than not, it will outlast the new Kia.

Warranty, I have never had one. I have also never really needed one.

I thoroughly research the type of car I need, and make sure it has a good reputation for reliability, that usually takes some years.

If it were me, I would go for a 2007-2008 corolla, they had less issues. You can find plenty with little over 100k miles and price is very good. As was mentioned, kids have a tendency to...damage them, so don't worry about a perfect body or paint job.

Find one and give it some serious TLC preventative maintenance, and if she doesn't much like the car, she will really hate that it just won't die!