Various types of makes using it now, mainly in light commercial ie minibus etc. Peugeot/Citroen have been using a separate additive tank on their cars for years, with what was a fool proof way of putting a certain amount into the main fuel tank at each fill up (when the fuel cap was removed and replaced). What they never accounted for was the poor hard up person who might only put a tenner's worth in when they could afford to hence the additive got used too quickly leaving the DPF to soot up when running with no additive.
Tony.
Tony.