I'm Zlatko's buddy.
The Cayenne was developed with VW's Touraeg. It's the same platform, and a lot of the difference's are only esthetical.
The Touraeg v6 has a 24v 3.2L VR6 engine, which VW also uses in the Golf r32, Phateon v6(I think only in europe), audi uses it in their new 3.2L v6 quattro, and porsche in the base cayenne.
The 3.2L is an evolution of the VR6 engine. The vr6 started as a 2.8 and 2.9L(european corrado) Narrow angle V6. The VR stands for narrow V in german. It was originally a DOHC 15* v6 with 2 valves/cylinder. VW redesigned it in 2002. It was still a 15* DOHC engine with one cylinder head, only now it had 4 valves/cylinder, and the displacement was still the same at 2.8, but the head was changed quite a bit, and I've heard VW had a lot of problems fitting 24 valves in there. You can find that engine in 2002.5+ 6spd VR6 GTI's and Jetta GLI's.
Then for the r32, and other models, they bored and stroked the block to 3.2L, and changed the design of the ports a bit to increase the flow, but the engine is still a Narrow angle V6, in other words a VR6. It's still 15*, it still has one cylinder head. Just has twice the valves and more displacement, along with better flowing ports.
From what I've heard the VR6 name confused people, so VW and the other car manufacturer's using it just changed the name to V6, but it is a narrow angle V6.
I've seen diagrams of the head design. I'll try to find them and post em up here.
Here's a scan of the r32 engine specs:
And here's some specs of the Cayenne's 3.2L "V6"
3189 cc V6
84/3.31 mm/in Bore
95.9/3.78 mm/in Stroke
11.5:1 Compression Ratio