Volkswagen of America has launched what it bills as its “cleanest diesel ever for the US”, the Jetta TDI, which will go on sale in spring 2008.

The new TDI will meet emissions standards applicable in all 50 states, including the most stringent Tier 2/Bin 5 or LEV II/LEV requirements limiting nitrogen oxide (NOx) emissions to 0.05 g/mile.

This latest diesel Jetta for the US meets the lowest emissions standards without the use of urea injection.

Instead, a nitrogen oxide storage catalyst reduces NOx emissions by up to 90%. The engine management system changes operating modes periodically to treat the NOx that has been stored in the catalytic converter. A particulate filter in the exhaust system further reduces emissions.

The Jetta TDI is one of the first products of the BlueTec project initiated jointly by Audi, Mercedes-Benz, and Volkswagen. Their goal is to establish ‘Bluetec’ as a uniform label for clean and highly fuel efficient diesel-powered cars and SUVs with 50-state compliant engines.

The technologies individually developed by each manufacturer serve to reduce NOx in particular — an exhaust element more prevalent in a diesel engine.

Volkswagen unveiled its clean diesel concept Tiguan compact SUV at the Los Angeles motor show in November and that model will go on sale in mid 2008.

Volkswagen first sold diesels in the US in 1977 when it launched a Rabbit (Golf) model there. Since then diesels have accounted for almost 20% of its sales in the United States.

It offered a diesel Jetta until the 2006 model year but new emissions rules mean the diesel option is skipping MY2007 until the launch of the new ‘clean’ engine in MY2008.