The iQ utilizes a 3+1 seating arrangement where the passenger side of the dash board does not extend back as far as the driver side. This allows the passenger seat to sit further forward than the drive leaving room for an "adult to sit behind. The +1 seat behind the driver is strictly for the smaller of stature.
The prototype doesn't appear to have changed from the production model shown at Geneva and even with the extra seating capacity it doesn't look much larger than the Smart ForTwo. Toyota has not given any indication yet about whether they will offer the iQ to U.S. consumers although if gas prices keep rising, this could be a good alternative to the Smart.
[Source: Winding Road]