2009 Audi Q7 3.0 TDI Follow-Up Test and Video

Full disclosure: The 2009 Audi Q7 3.0 TDI clean diesel we describe here doesn't yet exist — sort of.

Don't get us wrong. Audi is committed to selling an Audi Q7 3.0 TDI with the very same fuel-efficient clean diesel powertrain, and it affirms that the vehicle will appear in showrooms during 2009. But it isn't yet clear whether the first examples of the Audi Q7 TDI will be officially homologated as 2009 or 2010 models.

Ah, technicalities.

Mileage Marathon
To us it matters not. We're cruising down California Highway 101 in a living, breathing preproduction example of a 2009 Audi Q7 3.0 TDI, nearing the finish of something called the Audi Mileage Marathon, a fuel economy competition Audi cooked up to show Americans the potential of the company's diesel engines.

Others in our group are driving TDI-powered A3s, A4s and Q5s — there's even a diesel-powered Audi TT coupe in the convoy. But those of us in Audi Q7 SUVs are the only ones competing in TDIs equipped with Audi's so-called ultralow emissions system that uses the increasingly familiar AdBlue urea solution that makes a diesel engine emissions-compliant in all 50 states.

The 1,000-mile route hasn't been easy. We joined the convoy in Las Vegas, where narrow two-lane roads descended below sea level into Death Valley, before climbing unsteadily to 7,500 feet for the night. From there we topped 9,945-foot-high Tioga pass on our way into Yosemite National Park. Day Two ended in the sleepy seaside town of Monterey, California.

Hypermiling, Schmyper-miling
The rules are straightforward. There's a suggested route, but we don't have to follow it as long as we show up at the designated lunch and overnight stops. Low-speed hypermiling techniques are discouraged by a scoring formula that simultaneously values mpg and average speed; go too slow and you'll shoot yourself in the foot. Officials refuel and seal the tanks themselves to prevent clandestine top-offs.

Within that framework, our strategy focuses on what was left unsaid. So we inflate the tires to the maximum, we keep the A/C off and the windows up (yes, even in Death Valley). We keep the engine revving in its 1,800-2,000-rpm sweet spot and cruise at 60-65 mph in 6th gear.

On a couple of stages, we even tape the hood seams and fit homemade wheel pants over the rear tires. We know these aerodynamic measures don't amount to much at the speeds we're traveling, but the psych job it does on our competitors is priceless.

More important, the mountainous terrain provides us a chance to unleash a fuel-saving technique unknown to our competition: We coast down long grades with the transmission in Drive instead of Neutral. An idling engine burns fuel, but an engine control unit maximizes engine braking by completely cutting off fuel while coasting in gear. We used this knowledge to good effect while descending from 10,000 feet to sea level.

Soon after we roll across the finish line in Santa Monica, California, we learn that we've topped the Q7 field. Our trip average of 30.2 mpg was the most frugal and our 49.8-mph average speed was second fastest. Yes, the fuel economy potential of the 2009 Audi Q7 3.0 TDI is for real.

Let's Get Really Real
After the event concludes and we're free from the need to treat the throttle pedal as if it were fabricated from delicate eggshells as we drive this Q7 back to Los Angeles for track testing, we quickly appreciate the authoritative way the TDI diesel gets off the line. This is an expected revelation, as the big Q7 had shrugged off the steepest grades in Death Valley while maintaining cruising speed in 6th gear. Still, it's nice to confirm that 406 pound-feet of peak torque can deliver the goods in suburbia, too.

In fact, that torque makes our turbocharged, 221-horsepower 3.0-liter V6 diesel feel stouter and more drivable around town than the 350-hp 4.2-liter gasoline V8 found in our long-term 2007 Audi Q7 test vehicle. The V8 emits a lot of powerful noises, but its 325 lb-ft of peak torque at 3,500 rpm pales in comparison to the TDI's 406-lb-ft wallop at around 1,750 rpm.

The Q7 TDI achieves 30 mph in 2.7 seconds and 45 mph in 5 seconds — 0.2 second and 0.1 second better, respectively, than the 4.2 V8 Q7. But the gasoline-fired V8's horsepower advantage eventually prevails above 45 mph, as our TDI Q7 achieved 60 mph in 8.3 seconds (8.0 seconds with 1 foot of rollout like on a drag strip), about 0.3 ticks later than the V8. At the quarter-mile, the TDI's 16.3-second arrival at 81.5 mph trails the V8 by 0.4 second and 6.5 mph.

On the fuel economy front, our 2009 Audi Q7 still shines. But, as expected, it didn't display the ruthless efficiency we saw on the Mileage Marathon. EPA certification tests are not complete, but Audi suggests that 18 or 19 mpg city and 25 mpg highway ratings are likely.

That sounds about right. We recorded a 22.7 mpg average in just over 1,500 miles of our usual mixed "normal" driving — 0.6 mpg better than the five-seat 2009 Mercedes-Benz ML320 Bluetec. What's more, the big Audi posted an eyebrow-raising 24.1 mpg over our 110-mile test loop through Orange County, a route with zero freeway miles. The Benz ML diesel recently managed only 20.3 mpg over the same course.

Cruising Correctly
Once up to speed, the diesel Q7 feels little different from its gasoline-powered counterpart. The steering is pleasingly accurate, if not a tad light in the effort department. Background noise levels measure a decibel or two lower than the V8 when cruising at freeway speed. Yes, there is a bit of muted diesel growl when maneuvering in parking lots, but it only draws attention to itself with the windows down.

To enhance fuel economy, the 2009 Audi Q7 TDI wears Michelin Latitude Tour HP low-rolling-resistance tires in a narrower 235mm tread width (our V8 wore 265/50R19 rubber). They deliver a smooth and quiet ride, and handling remains secure and predictable in tight going.

But our instrumented tests reveal slightly reduced limits. Stops from 60 mph now take 132 feet, some 9 feet longer than our V8 managed with its wider tires. Slalom and skid pad figures sink from 60.2 mph and 0.82g to 57.9 mph and 0.79g, respectively. These are decent results, but it's clear the TDI-powered Q7 SUV gives up some performance in the name of fuel economy.

Everything Else
Other than the engine, a TDI Q7 is pretty much the same animal as a gasoline-powered one. The options list is identical to the 2009 Q7 Premium with the 3.6-liter V6. The interior has the same high level of fit and finish, and the MMI system is about as easy to use (or clumsy, depending on your point of view). In fact, the only tangible interior difference is the tachometer and its lower-than-usual 4,600-rpm redline.

Audi is positioning the 2009 Q7 3.0 TDI as a diesel alternative to the 3.6-liter gasoline V6 model. The starting price of the Audi Q7 TDI in seven-seat Premium trim is expected to be about $50,000 — about $2,000-$2,500 more than the comparable 3.6-liter gasoline V6 that's rated at 14 mpg city and 20 highway and requires premium unleaded.

Based on local fuel prices, we figure the payback time for the diesel option is less than four years. But even if it didn't pay back, choosing the diesel over the base gasoline V6 is still a no-brainer, as that motor's 280 hp and 266 lb-ft of torque is no match for the TDI.

Heck, most of us here would take the 2009 Audi Q7 3.0 TDI over the more expensive and more horse-powerful gasoline V8, and that's saying a lot. Clearly, the new crop of clean diesels is the real deal. May we have more, please? An A3 or A4 diesel sedan, perhaps?

Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, and the manufacturer provided Edmunds this vehicle for the purposes of evaluation.