V6 or V8?????
The V6 has more than enough pep for most situations, in my opinion. I drove several Panameras with v6 and v8 engines, and I found that I preferred the v6. The V8 is just slightly smoother, but the v6 feels so much more nimble and the handling was much better than the v8. I also like the extra space in the engine bay the v6 offers.
