It's in the Nav Settings somewhere - sorry I'm not 100% sure where but there was something in there about "dynamic traffic avoidance". I think there are radio-submitted traffic update services which it picks up on and if it can find a better route then it'll re-direct you..."the route has been adjusted due to the current traffic conditions" is what it will say. Once you set a route you can also look at the traffic updates along your route. To be honest Audi don't hype up the SD Nav enough as it's got some decent features built-in.
The radio updates are nowhere near as accurate as Google Maps, and sometimes I'm worried they're out of date - so it's sending me on a detour even though the traffic has cleared. But there was one occasion driving with my mate in the car behind on our way to Hove - stuck on the M25 - my SD Nav re-routed me via Heathrow while his TomTom told him to stay on the M25. I eventually got to Hove almost 1 and a half hours ahead of him. So it does work.
£600 is a LOT of money for a Sat Nav. But it depends how long you're intending to keep the car for as well and how you plan to sell it.
Personally if it was 3 years+ and I was planning to sell it privately...then I think £600 is worth it. Considering it's standard now on the A3, in 3 or 4 years time I'd expect future 2nd hand car buyers would expect it. Might help make it easier to sell.
You could go dodgy and find a mechanic somewhere to enable it, but you'll still need to buy the SD Nav card (
http://www.ebay.co.uk/sch/i.html?_f...udi+SD+Nav.TRS0&_nkw=audi+sat+nav+sd&_sacat=0)