Yes, the oil may be leaking on a hot surface and burning. You could smell this inside the car.
Antifreeze fumes can be toxic. Breathing them can cause health problems. If your vehicle is leaking coolant, especially from the heater core use care and repair the leak as soon as possible.
Your heater core may have a leak in it, allowing the fumes to invade the inside of the vehicle.
check for a leak more often then not it is the flex pipe.
If you smell gas fumes you have a leak. To fix it you must find the leak. Your nose is your best tool to find the leak. This can be very dangerous so I would find and fix the leak ASAP.
You should be able to clean it up if the problem is solved. Most batteries are outside the car- I wonder why you smell it at all. Battery acid is not especially toxic, but do not drink it, of course. I suspect that you smell something else. Could there be an exhaust leak or maybe the heater leaks antifreeze into the inside of your car.
This normally indicates a refrigerant leak. STOP USING YOUR AC IMMEDIATELY AFTER THE ACKNOWLEDGEMENT OF THIS SMELL!! The fumes from the fluid in your AC system are highly toxic. The leak needs to be sorted out before the AC can be used again.
two things, exhaust has a leak of gases or fuel leak from engine bay
exhaust leak or a possible fuel line leak
Gas leak.
The fumes are most likely coming from an exhaust leak. The leak could be at the converter, or somewhere else in the exhaust system.
worst than that... bronchitis, cronic bronchitis or even lung cancer... repair it as soon as posible... I had the same problem and now i have a bronchitis produces by those fumes plus the winter cold... but was mostly agravated by the exhaust fumes, which are very toxic.
Superoxide, which is formed when a few electrons inevitably leak out and combine with oxygen.