Hi,I have a 1.8 Hatchback the boot is quite small as I have a space saver spare wheel and that takes up a lot of room.The 2litre model the boot is even smaller as it carries the battery as there is no room under the bonnet for that model for the battery.
If I was you I would contact your local Toyota dealership and make an appointment with them to veiw the boot size taking your wheel chair with you as a gauge.The Toyota salesmen are helpfull.

I have a 2.0 ltr hatchback and the boot space is small. It's not an issue for the wife and myself as even when we travel, it's only ever 2 or 3 cases, but I doubt even a collapsible chair would fit easily. The Corolla tourer has much more boot space, so would be a better option.