Engine change after Q reg

[mr henderson]

So, supposing a car is being built and it's decided not to apply for an age related plate. let's also suppose that the engine fitted meets the emissions standards for its age.

OK, so after it passes the IVA it gets registered with a Q plate. If after a few months the owner then fits a different engine (for instance an engine from a (for instance) 2002 car) would the car now have to be fitted with a catalyst, and what standards would it have to meet at the next MOT?



If someone had asked me this question say a couple of months ago I would have said, then, that AFAIK it would only have to not show visible smoke. Now, however, I am not so sure. This stuff keeps changing. Anyone know what the current position is?