I found that it matters very little how much it was now, but how desirable it is. I just sold my 2008 Audi A4 - It was clean, lots of maintenance done recently (engine mounts, clutch, DMF, glow plugs, decent spec, 3.0 TDI Quattro and the like. 110k miles. Autotrader suggested 3.5-3.8k trade value, I've seen similar ones on eBay end at 4.3 - 4.8k at auctions. I still got £6k for it, although there was a bit of hassle involved due to many people just talking for days via ebay messaging and then not saying anything. An e92 Coupe LCI 330D won't be a million miles away when new price wise from an e92 335D M sport, but the later will be worth twice as much on the market.