The Mazda 3 is currently available only as a five-door hatchback or four-door sedan, but recent patent filings hint at a possible coupe version.

First spotted by CarBuzz, patent documents filed with the United States Patent and Trademark Office (USPTO) and European Patent Office show a car with the same basic silhouette as the current Mazda 3 hatchback, but with two doors.

A second patent application filed with the USPTO describes frameless doors, which would be a perfect fit for a Mazda 3 coupe. Interestingly, the document said the windows could be made of reinforced plastic instead of glass, presumably as a way to save weight.

Mazda frameless door patent image

Mazda frameless door patent image

As with all automotive patents, these documents don't confirm any production plans. Automakers often file patent applications to protect intellectual property that later gets shelved. Note that Mazda also recently filed patent documents hinting at a rotary-hybrid powertrain, once again stoking rumors of a new rotary sports car.

The Mazda 3 has never been sold as a coupe and, with the departure of the Honda Civic coupe and general shrinking of the compact-car segment, it seems unlikely that Mazda will introduce one now.

In 250-horsepower 2.5 Turbo form, the current Mazda 3 does at least offer decent performance. That's about as sporty as the compact car will get in its current incarnation, however, as Mazda has said it has no plans for new MazdaSpeed models. Those performance models are seen as conflicting with Mazda's current attempt to reinvent itself as a more upscale brand. The automaker also needs to devote more resources to electrification in response to stricter global emissions standards.