The newer cars nowadays have "closed fuel systems". When they're working properly, they don't vent to the atmosphere............which is different from your everyday gas can.
Gasoline vapors are heavier than air. So as long as there's no source of ignition close to your garage floor, there shouldn't be an issue storing a gasoline container in your garage. Leave a little room in the top of the container for fuel expansion - don't fill the container clear to the absolute top.
Even though the natural gas furnaces and hot water heaters that are in some of the garages are mounted up on a platform, I'd personally choose to keep any gasoline containers far away from those ignition sources.
Bill
