It’s been confirmed that diesels built before the introduction of diesel particulate filters (DPFs) will not undergo stricter emissions tests after Sunday, May 20.

Although subject to the toxicity surcharge (T-Charge) in London, popular oil burners like XUD-engined Peugeots and Citroëns (and scores of ’80s-onwards Land Rovers) will be smoke tested to the same standard as they are currently – that is, provided they predate the 2005-06 introduction of DPFs.

Don’t roll out the bunting quite yet, though: advisories, as we’ve discussed before, are to get tougher, with minor, major and dangerous categories producing an automatic failure in the latter two instances. Your modern diesel classic could sail through the exhaust probe test only to fail on more stringent examination of its tyres, bumpers and reversing lights.

Where older diesels stand a better chance of survival under the new advisory structure, a lingering doubt remains that we could be removing a disproportionate number of future diesel classics from the roads – cars that were originally supplied with DPFs and had them removed at a later date to improve performance.

The new MoT rules seek to heavily penalise post-2005 diesels running without DPFs. With substantial fines and costly refit procedures outweighing the residual value of many cars so equipped, many diesel-powered daily drivers now face an early trip to the weighbridge.