You are proabably right, but I think, that it will be too massive, on such a small car.
I also have to consider the WAF (Wife Approval Factor).
The whole back of the Yaris hatchback is problematic in an areodynamic view. Theres almost nothing behind the rear wheels, which probably account for most of the dirth thrown on the back hatch and window.
If you look at the car from behind, the cabin narrows in just above the fenders, and making a cammback fitting to this is difficult, so if I make on, it will end just above the rear lights.
But I will have to think more about this. The cd at 0.29 it not bad for such a short car, and before I come the the camback I will probabbly look at bellypan and rearwheel spoilers, backend splitter etc. which dosen't have such high impact on the WAF.
