Soldato
Thing is there is no seat there, I believe they are only licensed to carry 4 people, which is a bit odd. I'm sure everyone has occasions where they need 5 seats.
ST1 and 2 are classed as 5 seaters and have 5 belts etc. ST3 is a 4 seater.
if you want a 5 seater you buy a ST2. You can always buy a set of ST3 front seats later and DIY it.