The thing to do is look at all the reviews you can for real world mpg
car wow are quite good.
The only thing that has put me off van derived people carriers is that the rear seats generally don’t fold flat. So need to be physically removed and stored somewhere when you need the space.
some are really heavy if they seat adults comfortably.
Thats something I can’t do myself.
But they are usually great value and very practical otherwise.