Ever since news of car manufacturers cheating emissions tests broke out (dieselgate scandal) last year, many governing bodies and transport ministries around the world are prompted to carry out their own emissions tests. Japan is one of the latest.
Japan’s transport ministry MLIT (Ministry of Land, Infrastructure, Transport and Tourism) sampled six domestic car brands, specifically their diesel powered models, on highways and on regular roads. They found that the Toyota Land Cruiser Prado, Toyota HiAce, Nissan X-Trail and Mitsubishi Delica D5 emitted two to five times more nitrogen oxide than the standard level. However, emissions rose by as much as 10 times in some of the driving test!
However, neither of these vehicles are fitted with defeat devices or illegal softwares. The only cars to pass this test are the Mazda CX-5 and Mazda Demio (better known as Mazda2). This speaks volume of Mazda’s pursuit in perfecting the internal combustion engine, and one of the key factors in being able to meet such stringent emission standard is by lowering compression ratio; the Mazda2’s 1.5-litre Skyactiv-D engine operates at a relatively low ratio of 14.8:1, though some diesel engines go as high as 22.0:1. Find out what we think about the Mazda2 diesel, and why Bermaz Motor should have it introduced here.
The current laws only require in-lab tests, of which the standards are set on that basis alone. However, the Japanese government is considering new regulations which will take into account the cars’ real-world on-road performance, and hopes that car manufacturers will respond accordingly.
Emissions of nitrogen oxide are reportedly dependent on weather and style of driving. The tests however, have been extensively conducted, and all discrepancies between laboratory and road tests have been noted repeatedly.