This will help to cut emis-sions by up to 60 per cent, re-duce fuel consumption by 15 per cent, and produce no visible smoke.

Too much diesel fuel in the petrol will cause bad combustion, which manifests itself as poor starting, misfiring and visible smoke from the exhaust.

The vehicle fails if it has been tampered with or if it produces 'visible smoke of any colour'.

There was no visible smoke or dust.

The water, whilst it increased thrust at the temperature limit, prevented complete combustion often leaving a very visible smoke trail.