"GM is preparing a premium version of Theta. Reports differ, but the general consensus is that it is a combination of the current Theta and elements of the new Epsilon 2 architecture, with some Lambda components as well. So far, the only models are the Saab 9-4X and Cadillac SRX. Despite the fact that these vehicles are loosely based on Theta, which is often used for small CUVs, it is believed that these will actually be midsized, since many have predicted that the 9-4X replace the similarly sized Saab 9-7X. There are also rumors of 7-seater TE (Theta-Epsilon) models under development."
I was under the impression that the Saturn VUE was to be recycled re-engineered for Buick but it seems they're using the Delta platform instead.