Infinity G35X

I think it's part-time. Rear-only until slippage. I guess it allows you to have an RWD sport-sedan with less chance of getting stuck. And less chance of having to install tire chains in California's overly conservative chain controls (I've see chains required for 2WD vehicles when there was just a dusting of snow on the highway; I suspect that's a huge contributing factor to why we drive so many SUVs).

Nissan claims better handling from RWD than AWD as their justification for part-time. I suspect it has more to do with what they know how to build economically. The Murano is similar, except FWD-only until slippage.