air with exhaust smell inside the car

recently I noticed an exhaust smell from the air vent specially when the car
is in idle or on park, seems good when running. What could be the cause of
this? exhaust leaking, engine burning oil, or any possible cause?

My car is a 1992 accord lx with 110k miles on it and has a good MPG about 30
for most highway driving.

Thanks for any clue!

 

If its rusted out or you need a exhaust system, fumes could be entering.

If I don't have the heater controls, set to re-circulate inside air I get
fumes from the cars ahead of me.

Tom

 

Take it your favorite mechanic or a Honda dealership. They can have some one
set in it and start it up while the car is on a lift. The mechanic can
examine the exhaust sytem and attempt to determine where the smoke is
coming out. It's my guess that there is a hole--it could be very
small--somewhere in the exhaust system. If they find a hole--I advise you
to go ahead and replace that entire section of pipe and if you have the
money--install a new muffler if you have never had it replaced before.