My, my are we ignorant!
I don't even know where to begin with you, you are really that bad. I'll touch on some key points and let someone else step in to further and/or correct what I post, if they wish to.
The W-Body Buick LaCrosse and post-2004MY Pontiac Grand Prix do not share any common sheetmetal, with a possible exception being the roof panel as all W-Body cars shared a common roof line, design wise.
The 2008 Malibu is Epsilon I and the LaCrosse replacement is Epsilon II. They are on totally different platforms. Even so, none of the Epsilon I cars share a single piece of common sheetmetal (I want to say the roof panel may be shared, but I'm not 100 percent willing to commit to saying that), nor do the upcoming Epsilon II cars. However, there is some commonality between the Epsilon I Aura and Malibu in regards to the interior (lower door panels, door handles are shared, to name some pieces from the top of my head) and in regards to some very minor exterior details (side turn signals and door handles). But, other than that, they have nothing in common design-wise.
The Invicta name has been used previously on past Buick models, circa late 1950s and 1960s. No, it hasn't been around 30 plus years, but it is a name steeped in Buick's heritage and has little to no negative baggage. And who said a Malibu-scale advertising effort was necessarily a bad thing, anyway?
Next time, learn a few facts before you spew feckless drivel around.