as Bikingcatastrophe says there’s a fair bit of variation in size of the cars being discussed!
Octavias are one of the biggest of the smaller estates, Passats being based on the same platform I’d say more one of the smaller of the medium sized ones, they’re both actually based on a modified Golf base, but the Golf estate’s tiny (and very over priced!) it’s all a little subjective!
Rear wheel drive BMWs have less height, the 3s alright in side the cabin but the boot isn’t very big, 5s much bigger but you pays your money for a decent one.
If you can get on with the size of the Mondeo I hear really good things about them, I loved my old Focus (the last generation) but the new one’s too small.