Hi All,
I saw a 2011 Mazda 3 Hatchback live on the road yesterday. Difficult to see from the publicity photos on the Mazda website, but there are outboard bumps built into the spoiler.
MazdaUSA - Wireless Tour - Gallery
From directly behind this car, however, these bumps are quite pronounced.
They look to be additons to get the air going down the back of the hatch, and prevent air from tumbling in from the sides...