I didn't know about this but the V5 I was sent back in November for my new car is a red one.
Any second hand car buyer should always check the data held on record against the reg mark on the vehicle. For the <£10 it costs it could save a lot of heartache.
This is advisable when purchasing from a dealer and essential on a private sale.
'Car Data Check' in google will throw up lots of firms who can do it online there and then.
Once you have the data the one most important check is the VIN against A. The (seller's) V5 and B. The information you have gleaned online. If it matches both then all good. If it matches neither or the V5 only then the car could be bogus.
The VIN is the long number viewable through the bottom of the windscreen below where the tax disc goes. This is where it will appear on a Ford, others makes may be different.
The VIN through the windscreen will look something like this:
http://www.vinguard.org/vin.htm gives further info on where to find your particular VIN.