No smell (extracted by the carbon)but petrol vapours make you feel ill with blurry vision and you wonder if its CO till you check the carbon cannister under the wheel arch of all places. Under its cap is a fabric filter which gets soaked with rainwater even without driving through deep water. Once soaked it stops sucking air through carbon and enough petrol vapours keep getting into cabin to make you feel, often intermittent. Dry it off and you start feeling better although it soaks again. Will try something non wettable in future, maybe wire wool as nothing at all may cause longer term problem.

Must be happening to more than me. May mimic ME or you just think you're under par. Why don't they put these near the wheel spray under the wheel arches when there could be so many dry situations for them.