The figures will be based on unladen LCVs using the passenger car test cycle, which has become the common testing standard for vans too.

Mercedes Sprinter product manager John Reed said the details would be online sometime in January and published in a dedicated brochure soon afterwards.

What has created the impetus for some makers to divulge the data — long calculated in different ways for internal use, but rarely shared with the public — was this levelling of the testing playing field and an EU directive that emissions data for all goods vehicles under 3.5 tonnes must be monitored from 1 January 2008.

The only confusing element within the legislation is that it does not yet require van makers to make this data public. Many expect an EU stipulation to publish the data to follow, as has been the case for cars for many years.

Peugeot and Citroën started publicising some CO2 and mpg data from early 2007 with the launch of their respective Expert and Dispatch vans, and VW and Mercedes have published mpg figures on specific models for some time. Where vans have been adapted to passenger vehicles, mpg data has had to be made available for type approval reasons.