2012 Audi A3 TDI
Credit: Green Car Reports
To meet small diesel emissions standards in the USA, most manufacturers use urea injection.
Except Volkswagen.
Mazda had a small diesel under development which would also meet emissions standards without urea injection. They have missed a number of deadlines & have gone quiet on the matter.
So how is Volkswagen able to do what no-one else can?
USA's Environmental Protection Agency has discovered that software in Volkswagen’s TDI four-cylinder diesel is able to detect emissions testing cycles & reduce emissions in response. In short, Volkswagen has been cheating.
Mystery solved.
Over 480,000 VW & Audi vehicles recalled. Cost may reach $18 billion.
http://www.greencarreports.com/news/1100101_vw-audi-tdi-diesel-cars-had-defeat-device-that-violated-epa-rules-500k-cars-recalled-breaking
Update — Volkswagen has authorized an external investigation:
http://www.autoblog.com/2015/09/20/vw-external-probe-diesel-emission-scandal/ / announcement U.S. Environmental Protection Agency major automaker German carmakers Volkswagen Audi ordered recall half million popular TDI four-cylinder diesel vehicles sold U.S. 2009 to 2015 EPA TDI detect emission-testing cycles significantly reduce emissions cars software turns off emissions controls driving normally turns on emissions test Cynthia Giles EPA enforcement officer teleconference reporters defeat device software cars emit 40 times maximum level nitrous oxides permitted EPA regulations regulations Tier 2 Bin 5 carmakers sell diesels regulations urea injection more complex emission-control systems control nitrous-oxide emissions Volkswagen system separate tank holding urea injected aftertreatment system small four-cylinder TDI diesel VW's vehicles EPA limits urea injection Mazda high-efficiency diesel engine U.S.A. USA market urea injection several missed deadlines Mazda engine cost recall Volkswagen $18 billion Volkswagen America EPA investigation defeat device TDI diesel engines owners affected vehicles investigation European studies passenger-car diesel engines emitting far more Volkswagen Beetle Golf Jetta Jetta SportWagen Audi A3 TDI /
