thank you all for your reply to my problem, my car has only done just over 91,000miles, i have been to a gearbox guy and he says its not the gearbox, the noise is more of a humming noise which haapens at 40-70, it happens on 60 mph then stops then 70 then it goes quite. when you take your foot of the gas after 80 when the speed goes down, it make a noise at 70 then quite, the 60 then after quite,