Of all the things gearheads making the 2,600-mile Great American Run through the West will worry about – avoiding the cops, keeping the car intact, finding a bathroom before their bladders burst – the size of their carbon footprint is at the bottom of the list.

What a footprint it is. The 200 or so cars competing in the second annual race – an update of the famed Cannonball Run – will spew about as much CO2 in seven days as the average person generates in 16 years. Mention that to the drivers and they'll probably ask, "Yeah? And?" They know they'll take some heat from environmentalists, and they're unapologetic.

"How much more do they want to strangle the human race," asks race founder Tim "Maverick" Porter. "Why can't car enthusiasts have a little fun?"

The Great American Run descended from the Cannonball Run, the celebration of unfettered speed moto-journalist Brock Yatesfounded in 1971. The only point was crossing the country as quickly as possible. It was blatantly illegal and wildly popular – it's spawned two movies and several imitators - until the 55 mph speed limit and a lot of heat from the cops shut it down in 1979. (By the way, the current record for crossing the country stands at 31 hours and 4 minutes, set by Alex Roy and Dave Maher during a flat-out run that Wired wrote about.)

Porter, who's always had a thing for fast cars and open roads, brought it back to life seven years ago with an annual run through Europe. It came to the states last year and attracted 200 cars for a cross-country dash to Los Angeles. The rules are a little more strict than they were when legendary racing driver Dan Gurney quipped, "At no point did we exceed 175 mph" after winning the event in 1972. These days, entrants must average 61 mph. "It's still tough, but it's not flat-out," Porter says. "It's not socially acceptable to run flat-out anymore."

That isn't to say the drivers don't occasionally hit triple-digit velocities. "We don't break the rules," Porter says. "We just bend them a little." Still, Porter claims no one's ever been injured during one of his rallies and there's been only a few minor accidents.

This year's event, which starts Sept. 7, is a 2,600-mile loop through the West beginning and ending in Los Angeles. The route is top secret – "If it's published on a blog somewhere, every cop in the world will stake out the route" – but includes a stop at the Bonneville Salt Flats. Expect a wild assortment of cars – last year's fleet included a Bugatti Veyron, several Ferraris and Porsches, a lot of American muscle cars and even a GMC crew-cab pickup.

We were curious to know how big a carbon footprint the cars left. We picked 10 at random and used an online C02 calculator to determine their emissions over 3,000 miles. Multiply that by 20 and you get 648,000 pounds of CO2 for the fleet. It's unscientific, sure, but it gives you a ballpark idea. The Union of Concerned Scientists says the average person generates 40,000 pounds of C02 a year.

Registration is open, but you'd better have a healthy bank account – the entry fee is $20,000. Gasoline and carbon offsets not included.

Photo: Great American Race.