Yup. The government data (can be found at
http://www.vcacarfueldata.org.uk)
was supposed to be in the form of a data file for each year from 2001
through to 2008. More recently they've moved to a rolling database
which is updated by the vendors. Unfortunately, when I tried to merge
the data from the annual data files, I found that some models of car
had been removed from later datafiles, other models were missing
completely and, to cap it all off, some model/vehicle IDs had been
reused!
A good example is the Ford KA. Ford must have changed something on the
production line, as KA models built after about 2006 have a lower
emmissions rating. Unfortunately, the 2007 VCA data file re-uses the
same unique model ID for the KA and just changes the description from
"Ka" to "Ka 2006", effectively wiping out the older Ka model from the
data file. Bah.