I have a 2008 A4 Audi Cabriolet that I have been told at 75,000 needs a timing belt replaced. Is the timing belt metal? Is this a necessary change?

 

B7, No not metal.

Recommended interval is 110k miles. Either way, 70k I would. These are interference engines, meaning you break a belt and timing gets out of sync, then your pistons and valves smash into each other. Time for a rebuild. Knock on wood.

 

Yes, you need to replace it. Do it sooner rather than later. The corrected interval (from Audi) is now back to 75k/7yrs (this was the original, then they corrected it to 110k, then they had too many issues and went back to 75k). You should do the full kit with tensioner and water pump as well.

Like Dolamite said, if it snaps while running, the top end of your engine is toast.