Helpppppp

I have a Bravo 1.4sx on a N plate. If I drive with the windows down or the sun roof open I get a wif of exaust fumes (not pure fuel) inside of the car, however when the windows are closed and likewise the sun roof the smell goes away. It is obvious that the air flow carrys the smell ito the car - is this a common thing or should I be worried...

I have a '97 R 1.4sx and I get a fairly strong smell of fresh petrol once in a while. I've tried resealing the injector and air intake but no difference. There are no leaks that I can detect but it's definately coming from the engine bay