VW Introduces Concept Small SUV with New Diesel and BLUETEC
29 November 2006
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| The Concept Tiguan. |
At the Los Angeles Auto Show, Volkswagen introduced the new Concept Tiguan, a “small Touareg” that it will put on the market at the end of next year. The concept shown in Los Angeles is powered by a “Clean TDI”, a new diesel engine with reduced engine-out emissions combined with a BLUETEC-labeled NOx aftertreatment system.
The aftertreatment system uses a NOx storage catalytic converter and reduces emissions of oxides of nitrogen by up to 90% compared to engines known today.
A NOx-storage catalytic converter (lean NOx trap) is discontinuous—at λ >1, it stores NOx; at λ<1, it releases and reduces NOx. Additional fuel consumption may result from the catalytic converter regeneration.
(Urea SCR catalytic converter systems, by contrast, are continuous, with the hydrolysis and thermolysis of urea leading to the formation of NH3 which is in turn used by the SCR catalyst to reduce NOx.)
The Clean TDI introduced in the Concept Tiguan is also one of the first components of the BLUETEC offensive initiated jointly by Audi, Mercedes-Benz and Volkswagen. (Earlier post.)
Volkswagen says that it will provide more technical details on the Concept Tiguan in the first quarter of 2007.
Resources:
Trading NOx for CO2 and adding costs. Urea is made from natural gas using thermal heat from natural gas. Releasing considerable sequestered CO2 as result of conversion, transportion, and ultimatly reformation into NH3.
Posted by: Tom | 29 November 2006 at 10:18 AM
Tom -
actually, this particular VW model will use an NOx store catalyst rather than an SCR-based system. Either way, you're burning on the order of 4% more hydrocarbons than a "dirty" diesel in order to meet T2B5.
On the other hand, turbodiesels feature much better thermodynamic efficiency than stoichiometrically operated naturally aspirated gasoline engines - often the only alternate engine on offer for a given model. Deduct the wet from the dry and you still come out 15-25% ahead on well-to-wheels CO2 with a diesel (depending on engine design and load cycle).
Gasoline engines are already closing the gap, though, thanks to downsizing and turbocharging plus direct injection and other technologies, such as variable valve timing and lift, Miller/Atkinson overexpansion cycles, displacement on demand, stratified lean burn (in conjunction with an NOx store catalyst). Flameless HCCI combustion, which is expected to hit the market early next decade, is feasible in part load for both gasoline and diesel engines, albeit using very different approaches.
Technically, all of the above can be hybridized with electric drive systems. Unfortunately, the cost/benefit relationship of compounding many fuel-saving technologies is not favorable. Toyota's judicious mix was a key factor in the success of the Prius. Expect a number of different fuel economy approaches to co-exist in the market before the inevitable shake-out.
Posted by: Rafael Seidl | 29 November 2006 at 11:21 AM
what kind of MPG
Posted by: kevin | 29 November 2006 at 12:06 PM
When I look at that, I just see the next Golf.
Posted by: nemo | 29 November 2006 at 07:55 PM
Tom.
Most of the technologies you mention that will catch gas-power up with diesels can also be applied to diesels. If diesels use technologies like displacement on demand and variable valve timing they should continue to maintain their advantages. The new 3.0, V6 MB E320 BlueTec maintains a 40% fuel economy advantage over the E350, 3.5 V6 that has direct injection.
I know you bring up the point of costs by stacking these fuel-saving technologies, but some of these technologies are moving towards standard production, and should not be an issue for diesel engine designers to design within cost parameters.
Of course, gas-power does make head way with turbo-charging and direct injection, but the drawback is the requirement for premium fuel. Still--the fuel savings are worth the extra price per gallon. The VW FSI engine produces 200 horsepower and 207 lbs of torque that is real flat (1800-5000 RPM), and gets fuel economy estimated @ 26/32. The FSI is a 2.0, 4 cylinder. Conversely, VW's standard engine for the A5 platform is a 2.5 I5--naturally-aspired--that produces 150/177, hp/torque, respectively, and gets fuel economy estimated @ 22/30.
So far, in the U.S., however, these turbo, direct- injection varieties have gone exclusively towards performance, negating any fuel economy gains--doesn't this sound familiar with our auto fleets. VW also makes a 1.4, I4 turbo, direct-injection, but not for our horsepower-obsessed society. That would give the New Beetle, Rabbit, and New Jetta plenty of power with near TDI fuel economy. The 2.5 should be scrapped and replaced with this 1.4 as the standard. Americans, however, again demand more performance than we need, and would only shell out extra bucks for rocket performance; not fuel economy.
I would submit that HCCI is not gas power, even though HCCIs are being designed that will burn gasoline, as well as others that burn diesel fuel. I don't think the word "diesel" refers to the fuel it burns, but the type of engine it is. HCCI is closer to compression-ignition than spark-ignition, even if it is running gasoline. Hence the name, "highly-charged, compression-ignition". The first diesel engine was designed to run on peanut oil. There was no such fuel as diesel fuel at the time. Because petroleum was so abundant and cheap at the time, we developed petroleum-based diesel fuel to run in diesels.
Posted by: Gregory Faulkner | 06 December 2006 at 02:52 PM
A bit disapointing to see this design, when you know the "pretty final" concept car, which looked just great. At www.tiguan.com the real production model is revealed by the end of the month hopefully I wont loose all my illusions then. The site is not bad, check it out.
Posted by: suvfan | 15 June 2007 at 12:47 AM