A5 3.0 TDI V6 Black Edition - Over Revving

[Chris729]

I am looking for some help. I have an Audi A5 3.0 TDI V6 Black Edition Plus Coupe 2dr Diesel S Tronic Quattro which I have owned for 4 years with out any issues. Recently I have noticed that it sounds like it is over revving. I can be driving at 40mph, the rev counter will show 1100 -1300 rpm but it sounds like its at 3500+ rpm. Has anyone experienced this or have any idea what the issue could be? Asking here before I take to a garage. Thanks.