I noticed a considerable amount of drag on a customer's car past 80 mph, in what I would consider to be a very aerodynamic car. Approaching 90 mph, the amps go through the roof.
The car is a 240Z with smoothed front end (no factory headlights), ground effects, and no real mirrors to speak of. Will lowing the car help?
Also, there is a big air vent built into the front air dam... but I didn't think that would make much of a difference.