OK I've heard this "halo car" BS for about a year now. I didn't know what it meant before, but I think I have a handle on it now.
Apparently, the definition of a halo car is one that does not sell well, competely alienates the carmakers loyal customer base while remaining almost completly unknown to all others. Oh yes, it must also be a rebadged foreign car that is produced on the other side of the planet from the target market.
I guess the '88 "Pontiac LeMans" was a "halo car".
You can argue a "by design" low volume sales all you want, but you can not claim that this thing has drawn the public into the showrooms to check out the rest of the product line.
Two dozen VW owners who like this car... Hardly a marketing coup for GM!