Yea, that video clip of that race seemed to be the slowest race in history!! No way that Cary 50 would outrun that Chris Craft or that twin O/B boat, since the 50 was probably running low 40s the whole race!
Anyways, to answer the question about fuel consumption...the newer Cary 50 has twin 12V1602 TI MTUs coupled with ASD #12s and 28" 5-blade Rollas and burns at cruising about 80+ gallons an hour. We cruise at 40knots @ 2,000 rpms. The fuel tank has a 550 gal capacity. The Cary 70 has an 800 gallon fuel capacity with 12 cyclinder Deutz MWMs coupled with ASD #14s and 6-blade Rollas and burns around 100 gallons an hour at 36+knots @ 2,000rpms. The Cary 70 Turbine burns around 400 gallons an hour when cruising with the turbine on (same Deutz engs with a LycomingT150 turbine) since the turbine sucks about 300 gallons an hour when cruising.
Hope this helps!