Welcoming plans for an Ultra Low Emission Zone (ULEZ) in London by 2020, the Society of Motor Manufacturers and Traders (SMMT) said London should set the benchmark for the world’s great cities by implementing a scheme that demands “the very best in vehicle technology.”

The SMMT has called for an reexamination of the current proposals set out by Transport for London (TfL) to enforce the latest emission standards for both gasoline and diesel vehicles. This reflects the step change in clean diesel technology, and helps to ensure similar schemes across the UK and Europe are harmonized.

The implementation of the ULEZ will accelerate the take-up of ultra-low and low emission vehicles, but a harmonization of standards – a technology neutral approach – for petrol and diesel vehicles would strengthen the initiative, said Mike Hawes, SMMT chief executive.

Currently, the proposed requirements differ for cars and vans. SMMT is urging London to be more ambitious with a universal — Euro-6 — standard for both petrol and diesel vans and cars which would remove any confusion, strengthen the uptake of cleaner technology and bring air quality benefits sooner.

"Today's diesel vehicles are light-years away from those built just a decade ago," said Hawes. "Intelligent engine design and highly efficient exhaust aftertreatments, including particulate filters, capture over 99 percent of particulates and around two-thirds of NOx emissions. ULEZ proposals should support the introduction of these technologies now, technologies which are being introduced ahead of the ever-tougher legislative requirements which will be implemented over the next few years."

The current proposals for an ULEZ for London dictate the 2006-standard Euro-4 for gasoline vehicles and the latest Euro-6 for diesel vehicles. Given the introduction date of 2020, it would allow gasoline vehicles of up to 14 years of age to enter without penalty.

By this date the European fleet average will be approaching 95g/km of CO₂, whereas a typical gasoline car of Euro-4 vintage would have CO₂ emissions some 72 percent higher. Euro-6 petrol and diesel vehicles are on sale now and mandatory from next year meaning that under SMMT’s proposals, by 2020, qualifying vehicles would be up to six years old and would be reasonably affordable, potentially on their third owner.

Crucially, regulators can be assured that they will be delivering the air quality benefits as Euro-6 vehicles have engine management systems which constantly monitor and manage emission performance – a major advance on earlier models’ technology.

Underlining the progress made by car makers, SMMT also said that it is vital that the ULEZ actually delivers on congestion reduction to allow the automotive industry's new technologies to work effectively. There must be no side effects to the ULEZ which actually increase congestion or else any air quality benefits will be negated, according to the SMMT.

Average CO2 emissions for new cars in the UK in 2013 were 128.3g/km, down 29.1 percent since 2000. The 2013 figure marks a milestone as it exceeds the pan-European 2012-2015 target (sub 130g/km). Work on CO₂ reduction has been matched by technology to cut other pollutants, resulting in filters which capture over 99 percent of particulate (PM10) emissions. Nitrogen oxide (NOx) levels from diesel cars have also been cut by 64 percent since 2000.

Criticisms that vehicles fail to deliver real world improvements compared to controlled test cycle conditions are also being addressed, with the Euro-6 standards to include real world driving emission testing for the first time. This will give confidence to regulators and consumers alike that these new vehicles are delivering real benefits, according to the SMMT.

Those benefits include carbon reduction as diesel engines are key to reducing road transport CO₂ emissions. Diesel cars emit up to 20 percent less carbon than their petrol equivalents – essential if the UK and Europe are to meet their climate change ambitions.