Why does it always smell like the exhaust is leaking into the cabin?

What is your question?

I am restoring the 1998 xk8 coupe. The engine runs very well. Mileage is a little over100,000. The car when driving always smells like the exhaust is leaking into the cabin. Hard to drive because of the smell. We have had the car checked out & there doesn't seem to be any exhaust leaks. Any suggestions??

What makes this problem better or worse?

Seems to be all the time when running.

How long has your 1998 Jaguar XK8 had this problem?

the past 2 years.