Is it true an engine uses NO fuel when you take your foot off the accelerator?

Hello there - I'm trying to do various things to increase fuel economy - tyre pressures, gentle acceleration, emptying the boot, half filling with petrol etc. However I've read a couple of websites advising not to coast - saying that modern engines use no fuel when you just take your foot off the... show more Hello there - I'm trying to do various things to increase fuel economy - tyre pressures, gentle acceleration, emptying the boot, half filling with petrol etc.
However I've read a couple of websites advising not to coast - saying that modern engines use no fuel when you just take your foot off the accelerator completely - for example when going down hill. I drive a 10 plate peugeot 107 so I assume I would have one of these "newer engines" but - is this true? And if so - how does it work? How can an engine work if there is no fuel? I thought it was suck,squeeze,bang, blow? Are they saying the wheels then start just spinning the engine? Sorry if this sounds daft, I don't know as much about engines as I'd like!
8 answers 8