How fast can you drive across the USA?

The gear is all bought and loaded. Twenty packs of Nat Sherman Classic Light cigarettes, check. Breath mints, check. Glucose and guarana, Visine and riboflavin, Gatorade and Red Bull, mail-order porta-pissoir bags of quick-hardening gel, check.
Randolph highway patrol sunglasses, 20-gallon reserve fuel tank, Tasco 8 x 40 binoculars fitted with a Kenyon KS-2 gyro stabilizer, military spec Steiner 7 x 50 binoculars, Hummer H1-style bumper-mounted L-3 Raytheon NightDriver thermal camera and LCD dashboard screens, front-and-rear-mounted sensors for a Valentine One radar/laser detector, flush bumper-mount Blinder M40 laser jammers, redundant Garmin StreetPilot 2650 GPS units, preprogrammed Uniden police radio scanners, ceiling-mount Uniden CB radio with high-gain whip antenna. Check. Check. Check.
At the moment, the driver and copilot of this E39 BMW M5 are illegal in intent only as they obediently cow along the tip of Manhattan, funnel into the Holland Tunnel, and spill out into New Jersey along a six-lane mash-and-merge. The speedometer reads a cool 60 miles per hour; the clock reads 9:12 pm.