I use a halfords variable bike rack and it works perfectly! It will fit your yaris since it is designed so that it can change shape to suit most cars (except the citroen ax). It was about 65 quid and works very well! I think its called the high mount roof rack!
The buggy goes on rear axle at the top, opposite to the one on the pic above. No need to dismantle or anything you will just need some ties to help secure it.
I can fit both the buggy (flexifoil) and two bikes!
Hope this helps
Rick
P.s. it does fit on the yaris