For heavy vac work it can only be 230v, that’s what I use on Mrs Ridgeways wagon, think horses, dogs and lots of children..
In the house we have a Dyson stick thing, great for a quick zip around and some spot cleaning, also more than enough to clean my car every few weeks.
Good cordless is very convenient and will allow to do a job in a few mins, corded will allow a deep clean (animal hair, ground in dirt etc).
Can you justify a decent cordless stick vac for the house that then you can use on the car ?