When I thought of crisp corners on the sides, I immediately jumped to the new Impreza.
Upon closer inspection, it seems like Subaru used a fair combination of trip ridges and rounded edges. It seems they wanted to trip the air as much as possible without making the styling awkward, so they compromised and rounded the bottom of the bumper to continue that lower body line in the doors. This area probably doesn't matter much anyway, since it gets the turbulent air off of the rear wheels. It seems also that they tapered the body around the hatch, then tripped it at the end, which strikes me as ideal.