I get the same smell periodically...usually after I exit the highway.

I though it was due to my needing a head gasket, but after it was replaced a year ago, the occassional odor persists.

It is indeed coming from oil dripping onto the hot exhaust manifold, but I believe a leaky valve cover seal could also contribute.

Check for telltale signs of oil trails and scorched areas on the exhaust maniford...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car