Here are some specs on the Audi Q7 hybrid concept.

Although Audi has confirmed the Q5 as the first production Audi hybrid car, they did show a Q7 hybrid concept in 2005-2006 and as late as last year.  Since the Q7 shares the chassis with the VW Touareg hybrid and Porsche Cayenne S hybrid, who knows why they didn’t just make it 3 and offer the same hybrid drive train in the Q7.

The engine in the Audi Q7 hybrid

One possible reason is the engine.  The hybrid drivetrain used in the other cars could have bolted in but the hybrid concept used their 4.2L V8 engine instead of the 3.0L supercharged engine used in the production cars.  The concept’s V8 made 325 lb-ft torque and the electric motor added 148 lb-ft for a total of 473 lb-ft combined.  The reason it wasn’t made into a production car is because the 3.0L engine is more efficient, lighter, and makes as much power.

The gallery below shows the layout of the trunk mounted battery and the operation modes of the hybrid powertrain.

The nail in the coffin for the Audi Q7 hybrid

The final reason for introducing the Q5 hybrid before the Q7 hybrid was cost.  The car would have been too expensive for the US and Audi decided to focus their efforts on the Q5.  Early reports suggest that the Q5 hybrid will use li-ion batteries.