Is a used 2018 car a problem car?

They're either repos, fleet vehicles, or broken leases. Your best bet is to get ANY car you're interested in checked by a mechanic prior to purchasing.

All brands are for sale with 10 or 20 thousand miles. Mazda is no different.

It could be a lease, a demo or a rental.

I say go to the library and do some research...

They might have been rental or fleet vehicles.

The 2018 Mazda CX-5 is a very good quality and reliable vehicle. If the they are being resold only after a year it is likely the Mazda was a fleet or lease vehicle. If the seller can show you proof of prior ownership you will know whether or not to consider.

Many people buy a car and then discover that they can't afford it. Or they find out there's something about it that doesn't work for them. For example, I had a 1998 Subaru Forester and wanted to replace it with another Forester in 2015. I did plenty of research and was ready to buy one, when I realized the new model was wider than my old one. I did some measuring and found it literally wouldn't fit in my very old garage. I'd have to park on the street or pay thousands of dollars to have the old single doors on the garage busted out and replaced with a larger modern door. Had I not taken those measurements, I probably would have ended up trading in the Forester as soon as possible, especially after spending a snowy winter having to park on the street. For the record, I bought a Crosstrek because it fit. I've known people who got rid of new cars because they bought a small car and then discovered they or their spouse was pregnant, so they needed something larger. Or they moved and needed a more fuel-efficient vehicle.

Someone may not have been able to afford it and it was repo'd. They may have termed a lease. May have been a dealer demo car. Lots of good reasons.

First, be sure that you are looking at vehicles from a trusted dealership with a mechanic. It's hard saying whether or not the cars are in bad condition or not. Some people may have not been able to afford the vehicle, so sold it or could have just not liked the vehicle compared to others. Sometimes some cars are used as dealer cars, so it's in a way brand new but has miles on it because they used it for transportation for employees. Be sure to inspect the car (scratches, dents, interior, car accidents, etc)

Pick any car and look for it 2018 used and you will find them.