yes it does :thumbup:

but how well do you think theyd do under the car?

depends where... if you've got a full undertray they might help... otherwise perhaps on the rear axel...

if these things do what they should but in the wrong place you might well add a lot of drag! for example if they're upside down they'll direct the air UP, so if you place them under the front bumper won't they direct air into the engine bay? i'd use caution when installing these things in weird places!

The ebay item looks like they just used the shark fin antennas as their mold. Definitely wouldn't trust them to be functional.

~HA