Gunther Schiele, TDI Development, Volkswagen AG, talked to us about the NOX reduction system being used in the 2009 Volkswagen Touareg. This is a different system than the NOX storage catalyst in the VW Jetta TDI. Because the Touareg is heavier, bigger and has a bigger engine than the Jetta it needs a Selective Catalytic Reduction (SCR) DeNOx system. Watch the video animation as Schiele explains the SCR DeNOx system.
The nitrogen oxides are converted in the DeNOX catalyst using an organic matter that is a synthetically produced aqueous solution that contains 32.5% urea, known as AdBlue. The AdBlue tank is a four and a half gallon auxiliary tank located under the spare tire. The urea-based solution is continuously sprayed upstream into the exhaust gas stream. It is metered according to the mass flow rate of the exhaust gas. The exhaust gas changes depending on the driver. This means the urea will be used differently depending on how you drive. VW says the urea should last 6,000-10,000 miles. The AdBlue additive is non-toxic, odorless and biodegradable.
The Touareg V6 TDI Clean Diesel is powered by a 3.0 liter, turbocharged six-cylinder engine that produces 225 horsepower and 407 lb-ft. of torque. The V6 gasoline Touareg FSI gets 280 horsepower and 265 lbs.-ft of torque. The 2009 VW Touareg meets Tier 2, Bin 5/ULEV II standards and will be available for sale in all 50 states in the Spring of 2009.
Preliminary fuel economy for the 2009 VW Touareg is 18 city/25 highway, with a combined 20 mpg. The 2009 VW Touareg gasoline FSI gets 14 city/20 highway, with a combined 16 mpg. When I drove the gasoline car I got the EPA figures. When I drove the VW Touareg TDI diesel I got 24 mpg combined, 4 miles greater than what the EPA says I should have gotten.
Remember we had this problem with hybrids but in reverse. With hybrids the EPA overstated the mpg because of the way they calculate miles per gallon. The EPA uses a formula that includes the emissions from the tailpipe. Since hybrids don’t have emissions in the electric cycle of the testing the EPA overstated the mpg and had to change it. I’m wondering if the same thing might be happening to diesel in reverse: since diesel has different emissions than gasoline the EPA may be understating the mpg, which would give me more mpg in the real world.
There will be a premium for the diesel vehicle, and right now there is a premium for diesel fuel. The price of diesel fuel should come down in the next couple of years, but right now we are paying for transforming our diesel fuel into clean diesel fuel, from 300 parts per million to 15 parts per million. This clean diesel fuel has been produced in Europe for years. The clean diesel fuel is what allows Volkswagen to bring these vehicles into the United States. Diesel vehicles make up over 50% of the cars in Europe.