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The Vehicle Emissions Prediction Model (VEPM) has been developed by Waka Kotahi NZ Transport Agency and Auckland Council to predict emissions from vehicles in the New Zealand fleet under typical road, traffic and operating conditions. The model provides estimates that are suitable for air quality assessments and regional emissions inventories.

Since its release in 2008, VEPM has been successfully used in Auckland and around New Zealand to estimate vehicle emissions in air quality assessments for road projects. An important feature of the model is the ability to estimate changes to vehicle emissions in future years (out to 2050).

VEPM is a password protected Excel spreadsheet which is publicly available upon request from Waka Kotahi ( Please add 'Vehicle Emissions Prediction Model' to the subject line of your email when requesting the password. A summary of the previous and current versions of VEPM are provided below. 

Users of VEPM 6.1 can download the spreadsheet at the below link subject to the following disclaimer.


Waka Kotahi does not represent or endorse the information, content, presentation or accuracy of this vehicle emissions prediction model and its contents. This model may also contain information, advice, opinions and statements of third parties. Waka Kotahi does not represent or endorse the accuracy or reliability of any information, advice, opinion, statement or other information provided. Reliance upon any such information, advice, opinion, statement or other information, shall be at the user's own risk.

Waka Kotahi does not accept any responsibility or liability whatsoever, whether in contract, tort, equity or otherwise, for any action taken as a result of reading, or reliance placed on Waka Kotahi because of having read, any part, or all, of the information in this model or for any error, inadequacy, deficiency, flaw in or omission from the model.

Version Notes
VEPM 5.1 Previous version of the model released in 2012.
VEPM 5.2 Beta version of model, which was not formally released but has been made available on specific request. This version includes updates based on vehicle kilometres travelled (VKT) data from the Vehicle Fleet Emission Model (VFEM) provided by Ministry of Transport. 
VEPM 5.3 Changes from the previous VEPM5.1 released in 2012. This version incorporates nitrogen dioxide, speeds for light vehicles up to 110km/h, updates to the emission standard introduction date and country of origin assumptions, updated emissions factors for Euro 5, Euro 6 and Euro V based on COPERT, and addition of Euro VI category.
VEPM 6.0 Changes to the previous version VEPM5.3 released in 2017 include: Updating the fleet and extending VEPM to 2050, creating separate categories in VEPM for light duty hybrid, plug-in hybrid and electric vehicles, adding a new category for electric heavy-duty trucks and buses, updating all Euro emission factors with emission factors from the latest version of COPERT, incorporating new Euro 6 emission factors for passenger and light commercial vehicles, updating the method for calculation of tailpipe CO2 and updating brake and tyre wear emission factors.
VEPM 6.1

Current version of the model [ZIP, 33 MB]

Changes to the previous version VEPM6.0 released in 2020 include:

  • changes to significantly reduce bulk run processing times and rationalise the spreadsheet model
  • replacing all existing Euro emission factors with emission factors from the latest version of COPERT (the EU standard vehicle emissions calculator)
  • incorporating articulated truck emission factors and estimated VKT into VEPM
  • incorporating bus emission factors into VEPM
  • incorporating New Zealand real world fuel consumption correction factors for diesel passenger cars and diesel light commercial vehicles.

Waka Kotahi has prepared a VEPM user guide which describes the modelling process and the background for the VEPM method. The VEPM user guide and a summary of the development of VEPM are provided below. Additional supporting technical information can be found in the research reports which are referenced from the user guide.

For further information contact