Toyota officials say that the denox catalytic converter with hydrocarbon trap has been used in Toyota gasoline engines since 1992. "German manufacturers are also using this technology, without any problems it seems," a spokesman says.
He says that "to get an understanding of emissions during real operating conditions," the system had been tested in 60 vehicles in several different European countries before the Avensis D-Cat was introduced in 2002. The result was "clearly positive" regarding the "drastic reduction of particulate and nitrogen oxide (NOx) emissions. They are significantly below euro 4 levels, even when taking durability criteria into account."
Referring to a new diesel model series, Toyota also points out that the system is continuously being developed. The model Toyota refers to is the D-4D-Clean-Power with four cylinders and 180 hp, which will be launched this summer. According to Toyota Magazine, the system's engine management can regenerate the charge of the catalytic converter with hydrocarbon trap. "That way the purification power remains on a high level."
The CEO of a Toyota supplier sees it differently. He speaks of a "bad combat situation" and says the D-Cat emission problems are known.
The Japanese have been in "absolute despair" for several months now because the purification of exhaust emissions only works partly, he says.
He says that the engine has a "durability problem of a chemical nature." The supplier's own tests showed "that after 20,000 to 40,000 kilometers, not even the euro 4 levels are being reached."
BMW's head of development Burkhard Goeschel is generally skeptical. "I don't believe that any diesel can comply with NOx reduction levels after 2007 without adding urea." He says that only the so-called SCR technology can achieve this. It is used in heavy trucks and successfully treats emissions catalytically using urea as a reducing agent.