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Discussion Starter · #1 ·
Ok, I needed to make up for that last poorly written article. This one is good. Good picts. too:

First Drive: VW TDI's Proving diesel isn't just for heavy trucks

By Tim McKinney
Photography: By the Author

The chuckle came unbidden and unstoppable. Not the polite noise acknowledging the groaner just told by the salesman seated next to you in coach. No, it was the kind of quiet joyous laughter that comes only when all-is-right-with-the-world meets it's-good-to-be-king and 553 lb-ft of torque answer the prod of your right foot. Volkswagen had turned us loose with the new V10 Touareg TDI and I chuckled all day long. If you've read this far you, need a rig with a 7,700-lb towing capability and can afford the $63,000 (with the optional Premium Package), stop reading now and call your dealer. Supplies of the new V10 are severely limited and the US is scheduled to receive only 440 Touareg TDIs this year.

Diesels have long been popular in Europe, not just for heavy trucks but accounting for around 40% of registered passenger cars as well. Recent new car registrations in the EU are running 48% diesel. Saab says the new 9-2X is North-America-only because of the lack of a diesel option. Volkswagen also points to the Great White North, where 40% of the company's Canadian sales--and 70% of Jetta wagons, eh?--are diesels. But diesel passenger car registrations are less than 1% in the United States. Mention diesel and most people here think dirty, smelly, noisy, clattering contraptions. Obviously, "We've got to bust some myths about diesel in America," acknowledges VW's Len Hunt.

In 1990, new emission regulations in Europe forced manufacturers to develop clean(er) diesel technology. Work on injection systems, the combustion process and exhaust gas treatment not only reduced emissions by 90% but found huge gains in torque and horsepower. Sales of diesel powered passenger cars exploded. Now, with rising gas prices and state-of-the-art "Pumpe Duse" unit injector technology coming ashore for the first time, Volkswagen and technology partner Bosch think the same thing will happen here in the States.

Surprisingly, their most important argument for diesel power is performance. According to consumer surveys fuel economy is important but, "It's really the fun-to-drive factor, quick acceleration and pedal response, that sells vehicles in Western Europe," says Bosch's Marcus Parche. The heavy components required to withstand a compression ignition engine's greater internal pressures limit maximum rpm anyway so most diesels are long-stroke designs (good for torque, bad for revs) with up to 50% more torque than a comparably sized gasoline engine. Fuel economy is another plus, roughly 30% greater (diesel fuel not only contains 11% more energy than gasoline but also requires less refining) while CO2 emissions are 20- to 25% lower.

Fifteen years ago Volkswagen decided direct injection using a unit injector (one per cylinder) held the most promise for increased pressures and future applications. Deep in common rail development, Bosch was slow to warm to the idea but VW, who will deliver some 2,000,000 diesels this year, convinced them to join in. The result was "Pumpe Duse," combining the mechanical fuel pump, ECU driven solenoid control elements and direct injection spray holes into a single, compact unit. Built to incredibly precise tolerances (at or under one micro-meter or .00004 in.) the pump can deliver fuel pressures of 2,000 bars (or 29,000 psi and about 20% higher than common rail systems) to the V10's five 0.15 mm injector holes.

The extremely fine spray that results burns more completely, helping power and emissions, and reduces particulate matter formation- something directly related to fuel droplet size. The electronic controls can cycle the injectors up to 10,000 times a minute, completing a full cycle in 1 to 2 milliseconds. The actual injection of 40 or so cubic millimeters (a drop of water) of fuel happens in roughly 10 micro-seconds (1/1000 of a milli-second)! Injection amount, timing and duration are extremely critical for both power and emissions in a diesel engine. A one or two cubic millimeter 'pilot' injection (the size of a pin head) ahead of the main injection starts the burn, reducing emissions and quieting the typical diesel 'clatter'. A similar 'post' injection can also help emissions or be used to 'regenerate' a particulate matter trap.

Oxides of nitrogen (NOx) and particulate matter (soot) are the diesel's biggest emission challenges and new regulations scheduled for 2007 will decrease current standards--already 90% cleaner than 1974--by 95%. With the introduction of the low-sulfur diesel fuel mandated for 2006, conventional catalytic converters could then be used to control NOx and Bosch has developed a particulate filter that will catch 95% of all sizes of soot and last the lifetime of the vehicle. Those gathered to introduce "Pumpe Duse" to the US are confident the new standards can be met. On the road, it is hard to believe you are driving a diesel. Except for a hint at idle, there is little noise outside the cars, we also drove a 2.0-liter Passat TDI, and absolutely none inside to indicate the powerplant's persuasion. There are no glow plug icons to wait for, no clouds of smoke and no funky smell.

2004 Touareg TDI

The new V10 TDI engine was developed with a dual purpose in mind, the steel fist of power for the Touareg wrapped in the velvet glove of highest luxury for the Phaeton. And it's a diesel so it should last forever. VW looked in the parts bin, saw a very nice in-line five there, thought V10 and came up with an exceptionally rigid 90-degree aluminum block with cylinder walls hardened by plasma coating for durability. The 18-degree crank offsets allow uniform firing spacings, a counterotating balance shaft smooths vibrations even more and the vee provides plenty of space for the water pump, water-cooled alternator and intake runners. A helical-cut gear train drives not only the cams but all the accessories--A/C compressor, two oil pumps, coolant pump, power steering pump- as well. No belts to replace. Ever. Cross-flow heads bolt through the block directly to a cast iron bearing tunnel for exceptional overall strength and rigidity.

A single geometry turbo has a single optimal point and leads to charging pressures rising with engine rpms until the wastegate opens, um, wasting energy. VW attacks this problem with ECU controlled step motors that vary the V10's twin turbo's turbine blade geometry based on engine speed, altitude, load and the position of the drive-by-wire throttle pedal. In an effort to keep charge pressure in the optimal zone over a broader rpm range, the turbine blades close down at low engine to use all the available energy in the exhaust gases and gradually open up as rpm and flow increase to both reduce backpressure and keep the compressor from speeding up too quickly. A new six-speed Tiptronic automatic transmission was developed for the V10 with gear ratios designed to better complement its unique power delivery.

All in all, our route through the Virginia countryside showed the Touareg to be a fine driving machine despite weighing nearly three tons. But word is the V6 version is underpowered and the V8 (14 city/18 highway) thirsty. The diesel V10 (17 city/23 highway) and its 553 lb-ft of torque seem a perfect match, especially if you do any heavy-duty towing. Over our 180-mile route, the big diesel never faltered, cruising effortlessly and very quietly at 85 on the interstate, responding instantly while being flogged down the back roads and despite the massive torque, never spinning a tire--unless we asked - while crawling up a wet red-clay fire road. And better yet, despite numerous laughter-inducing attempts to record the lowest possible instantaneous fuel mileage reading--our best was 3.6 mpg--we averaged just over 20 mpg for the route. I don't know if the V10's fuel efficiency is enough to offset the $15,000 premium over the V8 but the driving experience is first-rate. I'd be off to buy a Lotto ticket but until emissions improve, the V10 is a 45-state car not for sale in Maine, Vermont, Massachusetts, New York or California.

2004 Passat TDI
Read the whole article and vew the photography:

100 Posts
Thanks for the review!

My only question is this: He wrote that a "new tiptronic six speed transmission was developed for the V10 with special gear ratios designed to better compliment its unique power delivery." :confused2:
The transmission and gear ratios are identical for all Touaregs, the only difference for the V10 is final drive ratio. Does he suggest that this is a special transmission built for the V10 that all other Touaregs must use? or is he making the different final drive ratio sound like a big deal?

BTW, This car make me smile all the time too
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