Gas fumes in cabin - 2003 Mazda Tribute

You may have a defective vapor recovery system or a loose hose coupling between the filler and the tank. The recovery system can go bad after a lot miles/time. Also, overfilling the tank (going beyond 'one click') can damage the system.
I would replace the gas cap first, make sure it is the right kind, before having the VR system checked.

This could be as simple as a hole in the exhaust under the cabin area. I would also check that all cylinders are firing properly. They can do a fuel pressure test to make sure there is nothing wrong in the line as well.

Sounds as if your catylatic converter might be clogged and not allowing your egr to recirculate you exhaust fumes

Probably a cracked fuel line and you are losing fuel I am going through the exact same thing right now on my montero sport

fuel injector washer needs replacing when this fault occurs somtime it is not apparent some times you get a noise remove plastic cover on top of engine start up and look for carbon build up around any of the fuel injectors also for exhaust gas leakage the fumes are pulled in to the cabin via heater ducts mainly when vehicle is at a standstill good look.

Could be bad 02-sensors do you have a check engine light on,It allso has a cabin filter and gas fumes will come in from the outside

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leaky exhaust or if your tailpipe is not protruding past rear bumper fumes will accumalate in boot causing them to pass into cab

There are rubber gas line hoses under the hood & after a number of years they tend to leak ever so slightly. They are under the hood to the passenger side. You may need to replace these fuel lines. There should be a cabin filter but you must take the wiper motor screen off to get at it & it is on the passenger side. Good luck!

is the car on recirculate or fresh air? air from your aircon comes through the bottom of your front windscreen, make sure its clear and free of leaves or anything that can cause blockage to stop it from become damp inside the aircon ducts. if it is definately petrol fumes you may have an exhaust leaking from your engine bay, releasing the fumes into your cabin, that is the most common reason for petrol fumes in your aircon.