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Freight and retrofit

Clean vehicle retrofit accreditation scheme

The scheme certifies retrofit technologies that meet UK Government standards.

The clean vehicle retrofit accreditation scheme (CVRAS) focuses on larger vehicles such as buses, coaches, heavy goods vehicles (HGVs) as well as vans and minibuses.

  • There are no CVRAS approved retrofit exhaust emission reduction systems for either Euro 3 (generally pre-2004) petrol or Euro 5 (generally pre-2015) diesel passenger cars.
  • There are also no CVRAS approved engine replacement solutions, as changing the engine of a vehicle will not lead to changes in the Euro status or recorded nitrogen oxide (NOx) emissions with the Driver Vehicle and Licensing Agency (DVLA).

The clean vehicle retrofit accreditation scheme (CVRAS) supports the operation of clean air zones (CAZ). The aim of the scheme is to address the air pollution emissions from buses, coaches, heavy goods vehicles, mini-buses, taxis and vans. To learn more about CVRAS, download a free copy of Zemo Partnership’s Clean vehicle retrofit technology guide.


Our guide below will answer many of the questions you might have on the clean vehicle retrofit accreditation scheme (CVRAS), low emission zones (LEZ), clean air zones (CAZ) and London’s ultra low emission zone (ULEZ).

CVRAS Register

The CVRAS Register contains approved and CAZ compliant companies and emission reduction systems, searchable by make, model and engine type.

You can also download:


CVRAS retrofit vehicle type overview

Get CVRAS certified

Manufacturers of abatement equipment must get approved by CVRAS before it can be added to the list of approved devices available to vehicle and CAZ scheme operators.

Emission reduction systems will need to demonstrate robust technical performance before they can be approved. Manufacturers will also need to have quality management systems to certified, for example, ISO 9001. Please see the scheme documentation below for further details.

CVRAS application forms

Additional information

Last updated: 4 July 2024