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TAXI RETROFIT OPTION: Euro 6 engine conversions could be the cost effective path to cleaner cabs

Local authorities across the UK are bringing in Low Emission Zones (LEZ) or Clean Air Zones (CAZ) with the main aim to reduce pollution levels and improve air quality.

They're often found in areas with high levels of air pollution, usually towns or city centres.

In most cases, drivers will have to pay to go through these zones if their vehicle emits high emissions. If they don’t pay the fee, they may have to pay a Penalty Charge Notice (PCN).

Most LEZ and CAZ fees apply to diesel vehicles built before September 2015 which usually don't meet emission standards. In some cases, fees don't apply to petrol cars built after January 2006. Electric, certain hybrids and other vehicles with zero emissions are exempt from paying to enter these areas. Dispensation is also available for older cars, typically with Euro 5 engines which are converted to Euro 6 Standards.

According to Cybrand, a UK firm that provides retrofit exhaust and emission control solutions for diesel-engined applications, Clean Air Zones are rising in prominence across the UK and are showing no signs of slowing down.

Retrofitting existing cabs to meet Euro 6 compliance standards is seen as one way to eliminate daily charges and future proofing your taxi. Using a fully approved retrofit conversion will not only save money on fees, but it will also ensure that your taxi is less harmful to the environment which carries long-term benefits for everybody.


The accreditation required to become exempt from emission zone fees within the LEZ or CAZ is known as Clean Vehicle Retrofit Accreditation Scheme (CVRAS) and is administered by the Energy Saving Trust. Cybrand are the only approved installer with this certification able to offer a retrofit conversion on taxis which doesn’t involve a completely new engine.

On a standard Euro 5 compliant taxi, exhaust gas from the turbocharger passes directly into the combined catalytic converter and diesel particulate filter and from there through the silencer to the tailpipe.

On a retrofitted Euro 6 compliant cab, a new Selective Catalytic Reduction (SCR) system is installed into the exhaust system further downstream. This incorporates a thermo-electric element which helps to bring the exhaust to an ideal temperature to encourage efficient catalytic conversion. Together with the introduction of AdBlue, which is a diesel exhaust fluid, the SCR system reduces NOx down to levels that exceed the requirements of Euro 6.

SCR is beneficial because it reduces NOx by up to 90% and is one of the most cost-effective and fuel-efficient technologies available.


Cybrand’s German-developed conversion process, utilizing AdBlue and SCR, is the only accredited retrofit conversion method that doesn’t involve either a full engine swap or an electric conversion. This has a huge bearing on the cost of making your taxi LEZ or CAZ compliant.

The typical installation time is also only one day – considerably less than other conversion methods available. As well as that, Cybrand’s conversion does not modify the original engine. It’s an exhaust after- treatment that introduces AdBlue and an SCR catalyst in conjunction with electronic dosing and thermal exhaust management.

Cybrand AEC Ltd in conjunction with HJS Emission Technology has gained widespread Type Approval for this conversion. As part of the installation process, the appropriate documentation will be sent to Energy Saving Trust (EST) who then update the ULEZ/ANPR database, so your vehicle will automatically be exempt from emissions-related penalty charges.


Cybrand offer a user-friendly option for maintaining the AdBlue system. An SCR display panel is installed in the cab in a place of your choosing, for example the left underside of the instrument panel angled at the driver. The SCR display panel will alert the driver when a top- up will be due. It allows for the driver to tab through a menu, displaying the remaining AdBlue range in mileage before the next top-up will be necessary.

Topping up is a simple process, performed via the under-bonnet filling point which is subsequently piped directly down to the AdBlue tank which is discretely located externally, under the driver’s seat box.


The conversion is currently available for Euro 5 Mercedes Vito and Peugeot E7 taxis, and now added just recently, the LTi TX4. The price quoted in Summer 2021 was £5,195 + vat though for most cities implementing Clean Air Zones there are grants available through local government, generally for 80% of this amount meaning the typical cost to a taxi driver is just £1,234.

The cities involved presently do have slightly different processes for how to access this grant funding. Cybrand can direct individuals to the appropriate resource depending on their location if they require more support. The retrofit system also comes with a full 2-year warranty and local installation options are being rolled out continuously.


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