Each vehicle in the UK is assigned a Vehicle Registration Mark (VRM) and this is recorded in the STATS19 data. This can be used to check information about a vehicle and ensure correct vehicle weights and engine sizes are recorded in the statistics.
Statistics on vehicle registrations are published by the Department for Transport These registrations include both private and trade / company ownership which means that on an area-by-area basis they are not a reliable estimate of the number and location of vehicles at small-area level.
Analysis of collisions per vehicle registered are imperfect even at a national level as they do not take into account miles driven. For example, and analysis of motorcycle risk per registered vehicle would be misleading without taking into account exposure data.