I don't think "enormous costs" is a strong argument here. The annual MOT is usually under £50, and that includes a fairly comprehensive roadworthiness check and emissions check. A stronger argument would be that a car owner could change some settings on their car specially to pass the emissions check, and then set them back to dirty afterwards each year.
In practice, no, you can't. Certainly not without enormous costs such as mandatory regular vehicle inspections.
I don't think "enormous costs" is a strong argument here. The annual MOT is usually under £50, and that includes a fairly comprehensive roadworthiness check and emissions check. A stronger argument would be that a car owner could change some settings on their car specially to pass the emissions check, and then set them back to dirty afterwards each year.