Mercs and spender

I am considering a Mercedes-Benz SL350 Roadster from a MB dealer. First registered in June 2006, one lady owner (probably true) Jasper blue metallic, 20,915 miles, 3,498cc V6 Auto. It has extras: panoramic steel roof and COMAND satnav. It looks good. Asking £31,950. Is this a reasonable price and is there anything I should know or beware of?

Asked on 21 August 2010 by RB, Warrington

Answered by Honest John
This is the improved 272PS SL350 from March 2006 (246g/km on the V5C). In theory £31,950 is a good price against book retail of £33,425. But these auction prices from the ‘Fast & Furious’ sale at BCA Blackbushe on 5th June show that it’s now too much for market conditions where prices slid in anticipation of the June 22nd Budget.
Mercedes SL350 3.7, 2003/53, MNW £14,400s
Mercedes SL55 AMG, 2003/53, 43k miles £26,500s
Mercedes SL350 3.7, 2004/54, MNW £16,000s
Mercedes SL500 388PS 7-spd, 2006/56, 22k miles £29,400s
(That 388PS SL500 would have been a far better buy.)
Similar questions
After more than 40 years motoring I have it in mind to enjoy myself with a second-hand Nissan 350Z. As they are not popular for economy and duty reasons, I wondered if they might be making appearances...
In Glass's guide, valuations are based on trade-in: exc. ave. below ave, then retail and private. Where in the above would you expect auction prices to fit?
I use your website a lot as a reliable source of background information on new cars. I am thinking of changing from my current Porsche 996 Carrera to something with a little more luxury and refinement...
Related models
Looks good and make you look rich. 2006 models with increased power vastly better cars. 388hp 500SL plenty fast enough and makes a nice noise.
 

Ask Honest John Right column

Value my car