In the AutoblogGreen Garage: Audi Q7 4.2 TDI

Click the Q7 4.2 TDI for a high-res gallery
At the 2007 Detroit Auto Show, Audi made a big show of the Q7 TDI that they were planning to introduce to the U.S. market. That particular model is coming late this year or early next and will be powered by a 3.0L V-6 diesel. At the same show the Germans also showed a concept version of the Q7 powered (or should I say torqued?) by a new 6.0L V-12 TDI paying homage to the success of the R10 TDI Le Mans race car. Last month at the Geneva Motor Show, Audi announced that the V-12 Q7 would be going into limited production later this year.

In between those two diesel extremes lies a third Q7 TDI that's been available in Europe for the past year. This third model uses Audi's 4.2L V-8 diesel and it won't be coming to the U.S. market. However, thanks to the kind folks at Honeywell, we had a chance to sample a Q7 4.2 TDI recently in and around Ann Arbor. Like fuel and exhaust system supplier Bosch, Honeywell has a vested interest in promoting diesel adoption in the U.S. market. Honeywell is the owner of the turbocharger manufacturer formerly known as Garret and they supply turbos for many of the diesel engines currently on the market. To help promote the technology they have a fleet of current European diesel models that they are exposing to American media including this Q7. Read on after the jump to find out how the Q7 TDI comported itself.

The Q7 is a large SUV that shares its basic platform with the Volkswagen Touareg and the Porsche Cayenne although the Audi has a longer wheelbase than the other two and is the only one that offers a third row of seating. Anyone who's been following my ramblings here and on Autoblog for the last couple of years knows I'm not particularly a fan of SUVs, especially bigger ones like the Q7 which is very nearly as large as a Chevy Tahoe. The Audi is within an inch or two of the Tahoe in length and width, although it isn't as tall. Unlike the clearly truck-like Tahoe, the Audi has a more rounded appearance in keeping with it's lower slung siblings. The enormous and somewhat overwrought grille that "graces" all the current Audis looks particularly overbearing on this model.

As expected on an Audi, the Q7 propels all four corners via a six-speed automatic transmission and Quattro all wheel drive. Like the new A4, the Q7's Quattro system also has a 40:60 front/rear torque split which provides a slight rear balance for better handling under hard cornering. The Torsen differential mounted in the center allows the split to be automatically shifting an extra 25 percent toward whichever axle has more grip.

Given Audi's premium sporting pretensions, the heavily bolstered seats are similar to what might be found in a BMW or even a Porsche. For those so inclined, the auto box can be manually manipulated via paddle shifters on the back side of the steering wheel or by tapping the shift lever fore and aft (after first pushing it to the right to engage manual mode). The transmission is more responsive than most paddle shift automatics, but frankly the whole process seems rather pointless in this type of vehicle. Better to just put it in Drive and be done with it.

The Q7 is equipped with all the usual techno gadgetry including GPS navigation (unfortunately only equipped with European maps on this example), auto dual zone climate control, heated leather seats, backup camera etc. One useful feature on a big vehicle like this is the parking proximity sensors. When maneuvering in tight quarters, sensors at the corners trigger a audible warning along with visual indicators on the nav screen telling you which corner is about to hit something.

Selecting which of the myriad functions you control is done via the Multi-Media Interface (MMI) knob on the center console. This functions much like BMW's iDrive but Audi has a better software user interface. One of the available adjustments is for the adaptive air suspension. The driver can select among dynamic, comfort and automatic modes. Aside from increasing the ride height, I didn't notice any significant difference in ride quality among the options. Overall the Q7 handled well for a 5,400lb vehicle.

While the Q7 is roughly the same length and width as a Tahoe, it's several inches lower with a more sporting looking roof-line. For those that like to get some sun while they motor along, the Q7 offers a super-size panoramic sunroof. The main aperture covers the first two rows and the front half of the glass pops up and slides back over the back portion. A second smaller opening sits over the cargo/third row area and pops up but doesn't slide. The second row seats can be adjusted fore-aft and reclined. The test Q7 didn't have the third row seat installed so I can't comment on that. The cargo area has some rails embedded in the floor with tie down hooks that can slid back and forth.

What was truly surprising about this hefty beast was its willingness to increase velocity. The 4.2L V-8 produces 326hp and an immense 560lb-ft of torque. The thing I love about driving diesels and electric vehicles is the torque. Huge power numbers are fun to brag about, but when they come at stratospheric rpms, they aren't particularly useful. In the real world, low end torque is what gets the job done. It allows you to trundle along effortlessly in traffic and climb hills without running out of breath. However, when you have the kind of huge torque numbers this diesel has you can get some shockingly strong acceleration.

Pressing the pedal makes this Q7 get up and go in a hurry. This is one shockingly fast SUV that will outrun most cars at a fraction of the size and mass. For those that need towing capability, the Q7 4.2 has plenty with a capacity of 7,700lbs. That puts it 1,500lbs above the Tahoe hybrid which is touted as having exceptional hauling capability for a hybrid.

In its homeland, the Q7 4.2 achieves a combined fuel consumption rating of 21.2 mpg (U.S.). During its time in the ABG garage, the Q7 managed a pretty respectable 19 mpg which was all the more impressive given the fact that the engine encourages aggressive acceleration, a temptation I fell prey to. With more responsible driving behavior, the Q7 should be able to achieve numbers in the low twenties with relative ease.

Interestingly those numbers are pretty close to what the Tahoe Hybrid achieves. Although GM has declined to get specific about how much the Two-Mode hybrid system costs to produce, the off the record estimates I've heard from various sources all say it's substantially more than the $2,000-3,000 premium that a diesel engine costs. In 2009, GM will introduce their new 4.5L light duty diesel V-8 which should get performance comparable to the Audi V-8. It will be installed in a variety of GM trucks including the full-size pickups and probably the SUVs. It will be very interesting to see how the performance and fuel consumption of the GM diesel trucks compares to the hybrids.

In the meantime, the U.S. will definitely get the 3.0L TDI Q7 and we'll be trying one of those out soon. For those in Europe who crave a really fast and reasonably efficient luxury SUV, the 4.2L is a fine choice. We probably won't ever see this engine in the U.S. market given the oncoming fuel economy regs. But it was fun to drive for a few days. For those that don't need such a large vehicle (which is likely the vast majority of us) and like Audis, the brand will be introducing a new, smaller SUV very shortly. We can't tell you about that one just yet, but as they say patience is a virtue.