Mazda's biggest SUV switched over to much safer base-model headlights midway through 2020. Here's how to tell which version you're buying.

It's possible for an automaker to update its vehicles after agencies like IIHS rate them, and it's a common practice in the industry — even if it is confusing.

If an automaker goes to IIHS midway through the model year and says that it's improved a vehicle from a certain date onward, IIHS will often test the updated version and publish the new result, which is what happened with the CX-9. The IIHS then puts both results on its website and specifies which vehicles have which ratings depending on when they were built, as it has with the 2020 CX-9.

That's something to keep in mind with safety updates — they're not always as they initially appear. Automakers will often improve vehicles to get unfavorable ratings pushed aside or earn an award. It's what Mazda did with the CX-9.

And in Mazda's move to get that coveted safety award, it added one more layer to the buying process: consumers now have to confirm when a particular car on the lot was built if they want the new headlight.

That's because CX-9s with marginal-rated headlights are still for sale, which is the case with any car that goes through a refresh midway through the model year — making it important to know the difference between old vehicles and new ones, no matter the model.

Determining when a car was built is easy. All you have to do is check the sticker often found on the inside of the driver's side door frame, and it will tell you the car's manufacture date.

On new, base-model CX-9s, not doing that quick check could be the difference between top-rated headlights and inadequate ones.