2001 Vauxhall s Strong smell of petrol.

Hi there I drive a Vauxhall Zafira club 1.6 petrol engined car, However, over the last few weeks I have noticed that my car has developed a strong smell of petrol, and when travelling in a car behind my own it stinks. My fuel economy has also been hit to a point of me getting around 25 miles to a galon compared to the 50-60 I was used too.

Any help and support is greatly appreciated, if you have any pictures or diagrams that would help more, as I have very little mechanical knowledge.

Thanks again

Colin