Over the last decade or so Volvo have undeniably evolved into a premium brand to rival the likes of Mercedes, BMW and Audi, and the prices reflect this. If you choose to insist on a premium brand which is absolutely your right to do, you have to accept that the numbers won’t add up for a semi-fixed cost system – there’s no A6 avant or Merc E-Class estate on the scheme either, for example.
There are cars on the scheme as big as the Volvos, just without the Volvo badge. I’m not going to dig deep but I expect the Skoda Superb Estate, Ford Mondeo Estate, Peugeot 308SW and probably others have similar internal dimensions. If you NEED the Volvo badge (I personally am a fan of them so this reply is in no way dismissive of the brand – and drive an XC60 now, just a little unhappy with the tech levels in the last gen and the fuel efficiency) then Motability isn’t going to be the answer for you personally at the moment.
"Man is born in freedom, but he soon becomes a slave, in cages of convention, from the cradle, to the grave."