Flat changes, which are changes without using the clutch from what I can tell, are absolutely possible in every car. You just have to get the revs right. I enjoy the finesse it requires to do 'smoothly' and have done ever since my dad blew his clutch out and showed me how the fuck it was done by driving around London without using a clutch to shift gear for over a month while he got the money together for a fix. He did drive big ass double decker busses in london as well as trucks for years, so he was far from an 'average' driver as far as hours behind the wheels go though. Either way that was on a beat up old ford escort hatchback and I've done it in a Peugeot 206, a Citroen saxo, a Nissan micra, and a Fiat 500.