Rear Roof Spoiler Angle

[Toscane]

Well, here's the thing...

Yesterday I saw an Auris with TTE Roof Spoiler and it had the same angle with the roofs curve and sitting flush, going down with the line of the roof like this "_ _".

However, I saw couple of others, also with TTE Roof Spoiler and they had this small angle, going a little up like this "_ / ", well not that much but you get the idea.

Also I draw a small picture showing what I am trying to explain here, it's not a very precise drawing and the angle difference is not that much but there is a difference. Here is the picture:

I am asking because I might design my own spoiler yet it's highly unlikely because TTE is pretty much perfect for the Auris however, I don't want it to be mounted wrong. Also my only concerns are absolutely not the looks first, it has to be practical and has to be mounted aerodynamically correct so, what is the angle should it rise from the roof for the best aerodynamic results.

Thank you in advance.

[T600]

Use the same angle as the TTE.

It's a spoiler, not a wing.

[Fred6370]

The TTE spoiler is bolt on, so if some cars has an angel there, they have done something custom to it.

And the aerodynamic effect...... My guess is: none

I put in on my car, only because of the look.

[beowulf]

The TTE spoiler is bolt on, so if some cars has an angel there, they have done something custom to it.

And the aerodynamic effect...... My guess is: none

I put in on my car, only because of the look.

All the Auris I've seen with the spoiler have a straight angle. I think that is the original TMS (TF1?) spoiler.

I'm wondering if I should put it in my car but I really don't care about the looks.. I only want a bit more downforce since I drive 90% on highway. Thing is, I haven't seen any numbers or opinions on how effective the spoiler might be... if it's only for looks I'm not paying for it...