Thanks for all the input guys!
@ monster - The car will be kept for around 4 years. Getting one for 2 years and then replacing it really isn't an option. It took 8 years to convince my mum out of her Honda Civic into a CLK.

lol
@ wimmer - Yeah both cars are excellent. For my mum however, I'd lean a bit toward the C. We haven't yet driven the A4, but OZ reports have said the suspension is still overly firm for our roads and the steering numb. But we'll see on a back to back test drive. I also think the C's interior feels more premium in reality. The Audi looks cool though.
So the MB diesels and Audi Diesels are OUT. Since both are outdated and on the verge of being replaced.
The replacement for the 200k should be at least 12 months away?
There's still no official press for it, so I'd say around face lift time?
Audi peeps, how old is the 2.0TFSI unit in the A4. It's outputs look impressive 147Kw and 280Nm. My research says it was introduced in 2005. What about the 1.8T
Been crunching the numbers and the 3 choices presently are:
* MB C200k Avantgarde (135kw, 250nm, 8.8seconds, 8.4litres/100)
* Audi 1.8T (120kw, 225nm, 8.6seconds, 8.4litres/100)
* Audi 2.0TFSI Quottro S-line (147kw, 280nm, 7.7seconds, 9.7litres/100)
Anyone have the kickdown acceleration figures?