nuthing
exhaust leak or its running really rich
I would say it is the exhaust system.
yes nd it will also give of a oily smell with it
I would start by checking any leaks in your exhaust and fuel filter area, if there is any leaks throughout the exhaust the smell of gasoline or exhaust may come through into the interior.
most likely you have a leak in the exhaust pipes or a bad catalytic converter
Barring any fuel leaks I would say that your charcoal canister is probably in need of replacement. they can fill up with liquid after some time making them useless and will smell of gas. Also it may be an exhaust leak if it is not an actual gasoline smell.
The burning smell from the exhaust pipe may be caused from oil or transmission fluid leaking into the exhaust pipe. For example, if your turbo is failing on the car, then that can cause leakage from the manifold into the exhaust pipe. There may be other reasons, too, which other people will be better articulating.
What color is the smoke? Black - running rich. Bluish - buring oil. White - burning coolant. When you smell the gas, it is inside or outside the minivan? Back of the car or near the front?
Any exhaust smell in a car cab indicates an exhaust leak somewhere along the line. Th reason you don't smell it while driving is because the air flowing air under the car is blowing the exhaust gasses away before it can rise into the cab. After the car sits for a while, the gasses seep out of the leak, and up into the cab.
if you have a gas leak.
Its just the wax they have on them to stop them from rusting while in storage
Very strong would not smoke inside no getting rid of smell