From my knowledge, the only companies that share platforms with Kia/Hyundai are Daimler/Chrysler companies (i.e. SCoupe and lots of tiny Asian market cars).
Subaru was partly owned by GM (20%) and Saab was owned by GM from 1989-2009, until Saab was sold recently so that GM could earn a little money and stop ruining the brand name, personal opinion. Even when Subaru helped with the cross-platform, only the 9-2X shared anything with them. So let's not besmirch the name of one of the best brands out there by diluting it's credibility with an inferior manufacturer.