I don’t know anything about the MG and it’s boot size but have an Elite Traveller Deluxe secondary scooter that was/is used with a AutoChair LC Range 80Kg 4 way hoist.
The amount of room you need for hoist plus scooter is a bit like asking how long a piece of string is because apart from length of boots and scooters you have so many variation on how to load it for instance if your able to dismantle the scooter into four or five pieces or do you need to load it all in one piece.
As a rule of thumb you need to measure the boot length taking into account if you need the back seats to be usable or not and after that you need the height of the aperture of the back door. Once you have the height deduct 100mm (4”) for the hoists boon and from that measurement then what’s left is the height of you scooter with or without its seat in according to what you can handle.
Taking my case as an example with my car my Go-Go Lite Traveller goes into the boot complete however I upgraded (mid lease) my scooter to include all around suspension and this scooter cannot be loaded with the captains seat in place but fortunate for myself I’m able to remove the seat with the one good hand and one good leg I’ve got but you can see the complication that can creep in if your not wary.
Like others have said above, if you have decided on a car plus a hoist give your local Motability recommended hoist installer a call as I’m sure they would have fitted one before to that car.
The 80 Kg hoist will fit most cars and shouldn’t be a problem as indeed the 150 Kg version does as I had one of those in a hired car and was exactly the same model and size as my 80 Kg hoist but assume it had more powerful motors or gearing as the lifting tackle was the same and took up the same space.