[Number 3]

Not to bring data into the conversation, but

....................CTS................2011 5 Series..............2010 3 Series

Front Leg.........42.4".................41.4"........... ..............41.5"
Rear Leg..........35.9".................36.1".......... ...............34.6"
Frt Shoulder.....56.7".................58.3".......... ...............55.4"
RR Shoulder......54.7".................56.2"......... ................55.1"

And as the 2011 5 Series is off the same architecture as the 7 Series I would expect it to be a wider car.

Front and rear leg room of the CTS is very close to the same. And if you adjust the Front Seat to match the 5 Series, the CTS would then have almost an inch more Rear Seat leg room.