If you're one of the lucky few allowed to evaluate a BMW Hydrogen 7, you're free to roam about the country - albeit with a few restrictions.; The Port Authority of New York and New Jersey isn't allowing the hydrogen-powered sedan to drive in a number of tunnels.
The Port Authority is banning the BMWs - along with all vehicles carrying compressed flammable gases - from both the Lincoln and Holland Tunnels.; Hydrogen 7s will, however, be permitted on a number of bridges, including the George Washington Bridge - albeit only on its top deck.
The restrictions stem from the fact that hydrogen is extremely flammable.; The Hydrogen 7 uses compressed hydrogen as a gasoline substitute to fuel its 6.0-liter V-12 engine.; Although the hydrogen is stored onboard as a super-chilled liquid, the Port Authority fears the possibility of it returning to a gaseous state and potentially causing a fire or explosion.; Given a tunnel's limited access and air supply, such a disaster would be difficult for rescue workers to control.
BMW, however, has extensively tested the hydrogen system to prevent such an event from happening.; The hydrogen is so well insulated that a block of frozen ice would take over a decade to melt within the tank.; Any vapor that should happen to build up within the tank is released through a pair of roof vents in a controlled manner to reduce the chance of explosion.
While 100 examples of the Hydrogen 7 have been manufactured, only twenty were imported to the U.S.; Overall, the entire fleet has logged over a million miles without any serious incident.
Source: New York Times