Got the car on the SCCA corner scales. The gas guage was two ticks above the 1/2 mark. My best estimate, taking into account the amount of reserve fuel still in the tank after hitting the empty mark (2.5 gallons) is that I had about 10.3 gallons of gas in the tank. (it's a 15.9 gallon tank). I took everything out of the car, including the floormats, but left in the factory-supplied air compressor (the corner of the car where the air compressor sits was still the lightest!