We have the big DHB soft bags, in our Mondeo estate they would lie flat in the back with seats down, they would take up the full width of the car and about a foot of clear space lengthwise.
Changed to a Fiat Punto, for the last year we never even bothered trying to get the bags in the car, but last weekend we wanted to leave the bikes in a travelodge whilst we went out for the evening, took bikes up in car with bags folded on top. In the morning I thought I'd try and get the backs in for a chuckle…first one went in find, second needed twisting slightly to clear the rear glass. Amazed!
Spud…the only way you might manage it is to get a soft bike bag, fold it as best as you can and then pack the car with everything. When you arrive and unpack you can then put the bike in the bag for the hotel room.