Yep, the vent setting on my HVAC system doesn't work very well at all so following Badbents lead (
Roof Scoop) I put a vent on my car. I tried a scoop too (just something I had lying around) but it didn't have the desired effect so I'm back to just the vent alone, maybe I'll add the subaru style scoop some day but for now I'm too cheap.
Here's mine-
Robertwb70: Roof vent for my Metro