how to reduce exhaust emisions?

From your question I would imagine that you have failed the MOT on this. Assuming you have try these few things: Change the oil and fit new plugs, old oil gets contaminated with all sorts of nasties and if your engine uses a little oil in its normal running these will all add to the emissions. Check the air filter, and make sure the exhaust system has no leaks. If your car only does short runs, take it out for a motorway run to heat up and clean the cat to get it functioning to the maximum potential.

See how you go...

Good luck Steve

SB
November 2006