You have little or no chance of matching the quoted figures for fuel consumption. Read this:
http://www.dft.gov.uk/vca/fcb/the-fuel-consumption-testing-scheme.asp
This is the get-out clause:
IMPORTANT NOTE
The fuel consumption figures quoted in this guide are obtained under specific test conditions, and therefore may not necessarily be achieved under ‘real life’ driving conditions. A range of factors may influence actual fuel consumption - for example, driving style and behaviour, as well as the environment and conditions under which the vehicle is operated. Furthermore, since several different specifications (variants or versions) of a given model may be grouped together in the list, the figures used in this guide should be treated as indicative only.