Diesel particulate filters (DPFs) that wrongly claimed to be Euro V standard were only approved for Euro IV.
Three vehicle retrofit suppliers have been awarded almost £1m in Government funding to support the accreditation of new pollution-cutting technology.
Eminox is the first company to be approved for the Clean Vehicle Retrofit Accreditation Scheme (CVRAS) for the UK’s best-selling coach, the Volvo B9R.
Refuse trucks in Westminster are to be fitted with technology which cut nitrogen dioxide emissions by 99% during a recent trial.
Internal combustion engines are expected provide a cheaper and cleaner alternative to fully-electric powertrains in heavy trucks, according to industry experts.