Exhaust smell comes into cabin, Daewoo Lacetti 2004. Everything has been checked by mechanics no one can find anything. I start feeling badly after 1 hour drive.

 

Welcome to the forum... how did you manage to find a Chevrolet site working on a Daewoo ? since your engine is transverse I would suspect the connection of the exhaust pipe leaving the exhaust manifold , often times the exhaust pipe has a flexible coupling to allow of engine movement, after a while this coupling breaks down and the flexible part opens up allowing for exhaust gas to escape and be pulled in through the front vents at the base of the windshield...
A quick and easy way to find it is to shove a towel into the exhaust pipe blocking the flow ( you may need someone to hold it in place) and listen for the exhaust leak along the pipe and up to the manifold...
the vehicle will need to be running, in park and idling when you do this test...