rev counter

Good evening gents.When the five is parked up and reved the rev counter moves as it should so rises quickly with the rpm and then drops quickly as the rpm do.Driving is not so good.The needle dosent rise and fall as it should.It seams to slow.Any ideas?

Put ya foot down! ;)

Sounds like it might be sticking. I'd whip the clocks out and have a look at the back.