Home Media Magazine.
This may be the best proof of how real audiences feel about the film.
"[Cars 2] generated nearly half its sales from Blu-ray Disc—a significantly high percentage for an animated family film. The film’s strong showing on Blu-ray is due, in part, to its availability in Blu-ray 3D, which accounted for 17% of total disc sales."
Actually, restricting the availability of many bonus features to the 5-disc combo pack (which includes the film on Blu-ray 3D) was likely the biggest reason for higher 3-D sales.