There is a breather valve in the engine bay http://2009.bmwfans.info/parts/catal...urb_air_valve/
close to the charcoal filter.
For a quick test: the air breather valve should have a resistance of 45 ± 20 Ohm, without power it is closed.
Also check the drain pipe of the charcoal filter. When engine is running, the active carbon filter should be flushed with air automatically, this will re-renerate the active carbon filter and the fuel mist is led into the intake system of the engine.
There is also an expansion tank, on my E32 in the wheel housing of the right rear wheel, you have to remove the mud cover to see all the hoses. http://2009.bmwfans.info/parts/catal...e/fuel_supply/
The filler cap has no hole anymore for emission reasons, that was in the past. Some people however drill a small hole into the cap, but then on U.S. models you will probably get a CEL for large evap leaks, at least that is the case on my U.S. spec E36 M3, when my wife forgets to close the gas cap correctly.