Slowly but surely, General Motors has been revamping Buick’s product portfolio. In the last three years alone, the brand’s lineup was entirely overhauled, with aging vehicles being replaced with all-new models that enable the brand to reach a broader market while growing sales volume. But the Tri-Shield brand isn’t done just yet.

According to sources familiar with GM’s product plans, Buick will soon receive a two-door compact convertible. Although sources didn’t specify, it’s very likely that the model in question will be a Buick-ified Opel Cascada, much like the Buick Verano is a Buick-afied Opel Astra. Coincidentally, all three of the models in question, including Cascada, Verano, and Astra, share GM’s compact Delta II vehicle architecture. Notably, an Opel Cascada was recently seen undergoing testing in the Colorado mountains — lending credence to our sources’ intel that it is being adapted for Buick duty.

The reasoning behind our belief that the convertible in question will indeed by the Cascada is quite simple: it’s highly unlikely that The General would develop an entirely new convertible solely for Buick given the segment’s extremely low sales volume; couple that with the global alignment of the Opel-Vauxhall and Buick brands, and the existence of Opel’s Cascada, and the writing seems to be on the wall for the Cascada to wear Buick’s Tri-Shield in the markets where Buick is marketed (North America and China).

It’s worth mentioning, though, that Buick will most likely receive a convertible model before Cadillac — GM’s other luxury brand. And though an ATS Convertible (along with an ATS Wagon) are still possible, it’s highly unlikely that they will be introduced before the Cascada is adapted for North American markets as a Buick.

Expect the drop-top Buick to land by the summer of 2015, possibly wearing the Riviera nameplate.

The GM Authority Take

No matter how you look at it, this is pretty much a no-brainer. We expect the new Buick vert to be moderately popular in the U.S. while enjoying high sales volumes in China, where Buick is one of the strongest automotive brands.