Here's that MERC, doesnt seem to be taking the piss too much:
MERCEDES-BENZ
B CLASS DIESEL HATCHBACK B200 CDI BlueEFFICIENCY Sport 5dr Auto (ID:53550) HY12HVRValuation Reference
5UN-4QHF-E2U4
Mileage:4300 (09/01/2013)
Date of Registration:March 2012
VIN:WDD*******084
Colour:BLUE
Valuations
Trade In Clean£19,650 -
£20,950
Trade In Average£18,800 -
£20,100
Trade In Below£17,900 -
£19,150
The CAP link is on the Ford wesbite. Go to car configurator, select a car to configure and on the right hand side there is a box for finance. Inside the box is the link to 'value my car' and it takes you straight to the free CAP valuation site.