![A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018. A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018.](https://c8.alamy.com/comp/2CM03GR/a-market-ready-particulate-filter-retrofit-system-for-passenger-cars-to-avoid-diesel-emission-is-pictured-in-a-garage-of-german-exhaust-aftertreatment-technology-group-baumot-in-witten-germany-march-7-2018-picture-taken-march-7-2018-reutersthilo-schmuelgen-2CM03GR.jpg)
A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018.
![Buses retrofitting with diesel particle filters: Real-world fuel economy and roadworthiness test considerations - ScienceDirect Buses retrofitting with diesel particle filters: Real-world fuel economy and roadworthiness test considerations - ScienceDirect](https://ars.els-cdn.com/content/image/1-s2.0-S1001074217317643-fx1.jpg)
Buses retrofitting with diesel particle filters: Real-world fuel economy and roadworthiness test considerations - ScienceDirect
![A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018. A market ready particulate filter retrofit system for passenger cars to avoid diesel emission is pictured in a garage of German exhaust aftertreatment technology group Baumot in Witten, Germany, March 7, 2018.](https://c8.alamy.com/comp/2CNAPNT/a-market-ready-particulate-filter-retrofit-system-for-passenger-cars-to-avoid-diesel-emission-is-pictured-in-a-garage-of-german-exhaust-aftertreatment-technology-group-baumot-in-witten-germany-march-7-2018-picture-taken-march-7-2018-reutersthilo-schmuelgen-2CNAPNT.jpg)