Originally posted by: Zenmervolt
The roomiest car available for sale in the US is the Lincoln Town Car. It has more passenger volume than any other car sold in this country (excluding stretch limos). However, it's RWD. In terms of size for the money, the Mercury Grand Marquis has to be one of the best, though, again, it's RWD.
Given your requirement of FWD/AWD though, the Audi A8 and the Volvo S80 are probably the biggest, though the Lincoln MKS and the new Taurus are pretty large too.
Frankly, given your requirements, the desire not to consider RWD cars is hurting you because the two examples of gigantic interior volume in the US are both RWD. You'd need a set of studded snow tired for the winter, so I can understand the hesitation and preference for FWD, but your size requirement is really pushing you towards big old body-on-frame cars with RWD.
Still, look at the new Taurus, it should be large (only 9" shorter overall than the Grand Marquis) and have a lot of interior room. It also looks like it will be a decent value.
ZV