Most Minors have that oil/petrol aroma when you first get in but you soon get used to it
My daughter complained of a very bad petrol smell when driving the Trav today. I will check the usual suspect fuel sender seal, but is it possible for the flexible pipe from the filler neck to the tank to become porous and let out petrol fumes? The one fitted at the moment does feel very hard so may be worth fitting a new one. Is there a better material to use than that supplied by the spares suppliers?
Mine was perished and letting out fumes, I got a new one from Bull Motif and fitted it today, being new rubber its more flexible than the old one, it cost around £12 IIRC
Very bad petrol smell is more likely to be carb overflowing due to sticky float valve - or leaking fuel pipe feeding the carb. So check it out carefully - serious fire risk! If it 's the fill pipe you should see some dampness on the pipe (take the metal cover off and inspect) - and of course the smell will be localised at the rear of the car.