Europe's diesel debate is heating up as car makers and suppliers compete to market the most environmentally friendly technology, Automotive News Europe reported. At stake: substantial rewards for those backing the winning technology - and lost revenue and capital for the losers. At the centre of the discussion is what advanced technology is best suited to trap soot particles in diesel emissions and thus help car makers meet tightening Euro 4 pollution control norms. New no-maintenance systems that don't require additives are competing with filters whose efficiency is improved by a fuel additive.