Question to the Department for Transport:

To ask the Secretary of State for Transport, what recent estimate his Department has made of the number of diesel cars which have had their diesel particulate filters removed.

The Department has not estimated the total number of diesel cars which have had their diesel particulate filters (DPF) removed. However a check for the physical presence of a DPF at MOT was introduced in February 2014. Since this change was introduced, over 2,000 vehicles have failed their MOT for a missing or non-functioning DPF.