Is there smoke coming out of the
front of the tail lights? (See video at about 1:00 mark.) It's not much, but wouldn't that mean that the air is being sucked in from the back of the car through/behind the tail lights and rejoins the airflow on the side of the car?
I can't decide whether this is a good thing... but wouldn't that mean the pressure directly behind the car is lowered even more?
How about redirecting some air from the side of the car, duct it through the trunk area to fill the vacuum behind the car? (Not practical if you want to actually use the trunk, I know, but an ecomodder has no scruples, right?
)