I just did an interior spec comparison of the 2006 RX 330 and the 2011 RX 350. Here are the results:
Headroom Front - Essentially the same with the new RX being .2" less
Headroom Rear - The new RX has .9" Less
Legroom Front - The new RX has .6" more
Legroom Rear - The new RX has .4" more
Shoulder Room - Front - The new RX has .1" more
Shoulder Room Rear - The new RX has .5" more
Hip Room Front - Exactly the same at 55.6"
Hip Room Rat - The new RX has .4" more
I hope this helps you.