You can report any sightings of smoky diesel vehicles if they are public service vehicles (buses and coaches) or heavy good vehicles (lorries) to the Vehicle and Operator Services Agency (VOSA).
If you spot one of these kinds of vehicles producing a high volume of smoke, you can let them know;
- type of vehicle (public service or heavy goods)
- vehicle registration number
- company name
- where and when the vehicle was seen.
Once reported, VOSA will contact the operator, and if necessary require them to provide evidence of an approved smoke test on the vehicle.