the SVA is for vehicles that have been build or significantly modified from there original config, i.e. a kit car or changing a regitered bike into a trike, as i believe. it also applies to imports etc to ensure there compliance wi UK law.
this SUV wotsitmafloge is the kind of thing that exists in oz and NZ where you have to have your mods certified, or certified parts fitted by a certified dude. i think thats what it is. otherwise you get silly things like how in spain and france its illigal to mod your engine, hence crazy euro styling and in israel its illigal to mod full stop other then body, so no lowering or nothing!