The Touran is built on a Golf chasis, the Sharan (Sharon lol) and the Alhambra are built on the Passat chasis.
The original Mk1 Sharan/Alhambra/Ford S-Max were actually all the same car too!
For the Mk2, Ford dropped out and VW used the Passat B6 to build them.
The Sharan and the Alhambra are as you can imagine quite a bit bigger than a Touran.
I had a quick look and you could pick up a 2016 Alhambra with a 1.4 TSI for your sort of money...