Toyota Corolla 2009: Petrol smell inside

In regard to the pungent smell coming through the air vents when stopping experienced by Noel Fergus (Carsguide, Feb 21, 2014), I had the same trouble with our 2009 Toyota Corolla. Toyota could not find anything wrong, but suggested I try a higher grade of petrol, and that fixed the problem. When I went back to explain that the car was meant to run on 91-octane, they said to try a different brand of fuel, and since changing to another brand, I have not had the smell coming into the cabin at all.