At very low revs I have a slight rattle type noise as I accelerate. It comes from the engine. (almost a brrr) I hear it just as the rev counter passes over 1k revs thaen it goes as soon as the car starts to accelerate. It occurs in most gears but only at 1k revs - i.e when driving slowly I heard this on another S4 I test drove - is this normal? The brakes are also squeaking under light braking - not something I would expect from a car just having been serviced and had its 100pt Audi check!