:
I have Toyota Camry with 60,000 miles on it. On three separate
occasions I have noticed an acrid smell on the inside of the car while
driving on the freeway. I have switched the air recirculation from outside
to inside but that did not seem to make any difference. The smell is not
antifreeze/coolant and it is not exhaust smoke ( I don’t think). It is
also not hot oil or grease.
I not getting any indications that the car is running hot. Coolant and oil levels are normal. The car has been well
maintained and the performance and fuel milage are normal. I am thinking
it may have something to do with the fuel vapor recovery system – but the
smell is not like raw gasoline.  There are not any unusual smells around
the car when it is parked after driving and there are not any fluid leaks
under the car. It seems to do this every three or four days and when the
car has been driven for at least ten miles or more. I normally only drive
the car to and from work – a 17 mile trip each way.
Thanks for your time.
Sincerely
Charles
 Hello Charles,
Thanks for your email. Four things come to mind here.
1. Leaking heater core – which would leak coolant on to the passenger floor board up under the dash area. Pull back the carpet under the dash and feel around with your hand to see if you feel any wetness or oily substance. If you do, you have a heater core that is seeping coolant inside the vehicle and needs to be replaced or by passed and replaced at a later date.
Turn the heater on full blast and smell the vents and feel the carpet on the passenger side.
2. A problem with the A/C evaporator core, which again is on the passenger side inside the dashboard. Sometimes mold and bacteria grow on the evaporator and the smell will come out the A/C vents when you run the air conditioner. Smell the A/C vents with the air conditioner on, then smell the air out the vents with the heater on. If the smell is gone or different you probably have a problem with the A/C evaporator system.
3. A plastic bag has melted to the exhaust system or muffler. I have seen this MANY times. You can smell a burning odor inside AND outside the vehicle. We use a grinder and grind off the melted plastic from the exhaust pipe. Your oil change guy can check to see if this has happened. Plastic bags and other road debris can stick and melt to the exhaust system.
4. An exhaust leak which is letting stinky exhaust inside the cab of the vehicle. Again, your oil change guy can check for this. You can also plug up the tailpipe for a few seconds with a bunch of thick rags WHILE the engine is running. If there is a leak in the exhaust system you will hear the air leak under the vehicle. Be careful that exhaust out the tailpipe will burn your hand!
Other than that……I would get your mechanic to take a test drive with you and let them smell this smell first hand to get their diagnosis.
Blessings,
Austin Davis