Vehicle testing firm Emissions Analytics says diesels can be clean and govenments are highly unlikely to give up the fuel just yet.
Since the introduction of Euro 6 in September 2014, manufacturers have been forced to improve their after-treatment systems to meet the stricter legislated limits for NOx.
Exhaust Gas Recirculation, Lean NOx Traps, and Selective Catalytic Reduction technologies have been employed as part of a complex strategy to reduce tailpipe emissions.
Emissions Analytics said: "There have been variable successes, with some achieving the regulated limits even in real-world driving and the worst more than 20 times the legal limit. Overall, average NOx emissions from Euro 6 diesels are down 55% compared to Euro 5s.
"Nonetheless, there is still the fact that many new cars do not meet the legislated limits in real-world operation. Our data shows NOx emissions are on average 4.3 times over the limit for Euro 6 cars and, after a period of improvement, this Conformity Factor is rising. This is the heart of the issue, as to whether diesels are the major and unavoidable cause of poor air quality in towns and cities."
Consequently, there have been many suggestions made to combat the problem of dirty diesels. These range from the London Mayor’s T-charge, to a diesel scrappage scheme, to a total ban on diesel vehicles in certain zones.
However, Emissions Analytics says its emission data shows that modern diesels in their own right can be clean.
It added: "Since the launch of the Equa Air Quality Index six months ago, 12 cars have how achieved an A-rating including the latest Volkswagen Tiguan, meaning it has met the 0.08g/km limit in real-world driving."