The “race on Sunday, sell on Monday” mantra lives on at Audi AG, as the German auto maker prepares to unveil its new 500-hp Q7 V-12 TDI cross/utility vehicle at the Paris auto show later this month.

Benefiting from a marketing and development effort that earlier this year resulted in Audi becoming the first auto maker to win the prestigious 24 Hours of Le Mans endurance race with a diesel-powered vehicle, the new Q7 V-12 is the first production passenger vehicle to feature a 12-cyl. diesel.

Rated at 500 hp and 738 lb.-ft. (1,000 Nm) of torque – available between 1,750 rpm and 3,000 rpm – the new 6L twin-turbo mill also is the most powerful production diesel engine ever produced, Audi says.

Initial figures for the 5,500-lb. (2,495-kg) CUV are impressive: 0-62 mph (100 km/h) sprints in 5.5 seconds; an electronically limited top speed of 155 mph (250 km/h); and a combined fuel economy rating of nearly 20 mpg (11.9 L/100 km).

Although relatively close in size and output to the 5.5L, 650-hp V-12 employed in the R10 TDI Le Mans racecar, the new Q7 engine actually is a member of Audi’s 6-, 8- and 10-cyl. diesel V-engine family.

A compacted graphite iron (CGI) engine block, opposed to the R10’s aluminum unit, donned with aluminum cylinder heads forms the basis for the new engine.

A 60-degree cylinder angle reduces inertia from internal components and is the main differentiator between the V-12 TDI and Audi’s other 90-degree turbodiesel V-engines.

CGI, which Audi already uses in its European market 3L V-6 and 4.2L V-8 turbodiesels, is 40% more rigid and 100% more fatigue-resistant than cast iron. The material also allows for a 15% weight savings over cast iron, the auto maker says.

Internally, a 16:1 compression ratio is achieved through forged aluminum pistons and connecting rods, which share the same bore and stroke measurements as Audi’s 3L V-6 TDI. Overall length for the V-12 is only 6.5 ins. (17 cm) longer than the 4.2L V-8 TDI.

A new chain-driven valvetrain assembly is employed, as is a new high-pressure, common-rail fuel-injection system utilizing piezo-hydraulic-electric injectors. For the V-12, injection pressures are up from Audi’s current 23,206 psi (1,600 bar) to 29,008 psi (2,000 bar).

Other features include twin, variable geometry turbochargers producing up to 38 psi (2.6 bar) of boost; twin charge air coolers; and a double-flow exhaust system with twin particulate matter filters.

In addition to improving the common-rail injection system, Audi says it focused heavily on a new exhaust gas re-circulation system in an effort to meet Euro 5 emissions standards taking effect in 2010. It is not known if additional exhaust aftertreatment systems will be used to meet upcoming Tier 2 Bin 5 emissions regulations in the U.S.

Harnessing the V-12’s prodigious power is a strengthened 6-speed Tiptronic automatic transmission and Quattro all-wheel drive.

On the road, Audi says the new Q7 V-12 will have a unique and impressive exhaust tone. However, given the R10’s whisper quiet performance on the racetrack, visual cues – and gross displays of acceleration – likely will be the only ways to differentiate the V-12 TDI from lesser Q7s.

Major exterior changes include aggressive front and rear fascias; a chrome-plated, single-frame horseshoe grille; and larger brakes, wheels and tires.

Details about pricing and availability currently are unavailable, but a rollout in the 2008 timeframe is expected.

The Paris auto show is open to the public Sept. 30-Oct. 15.

msutton@wardsauto.com