When was it built? Audi made some major changes over the years, and some were in order to address issues.
IIRC the belts are due for replacement around the 100km mark.
If it has the s-tronic DCT then the most important thing to check is if it has had its first service - due around 60km.
Now I see MY13. Is that the American naming for a car built in 2012 or the real build year? The 3rd and final version of the s-tronic gearbox was introduced in Spring 2013.
Steering will be electric. Apart from the fact that some people don't like electric steering I think it is reliable.
In Australia they sell the 3.0 TFSI which is a de-tuned S5. The 3.0 TDI is faster than the 3.0 TFSI in stock formed but with a tune I think the 3.0 TFSI can reach the same output as a tuned S5 if my memory serves me correctly!
Sorry gents, I thought this was standard terminology. It's a 2013 A5. They did a 3.0L Turbo for both the A5 and the S5. I think there's another thread on this.
Unfortunately the sale fell through, but was thinking a 2013 model is probably a few years older than what I want.