My 1989 300SE has developed a smell that may be exhaust. I notice it particularly when I have been sitting at a light, then accelerate. Oddly, I do not notice it at highway speeds. I do not really think it is other cars--sometimes, I am sitting at the light alone when I accelerate and smell it.

I had the local muffler shop check out the exhaust, and all they could find was an exhaust manifold gasket leak, which they repaired. Clearly, the old gasket had been leaking--there was soot around several of the ports. There is no sign of leakage around the new gasket--no soot, and I do not hear any leaks.

Any thoughts on what might be the source of this smell, and ways though which it could enter the cabin?

Joe B.