coasting is actually worse than letting off when it comes to eco driving, if you leave it in 5th down a hill then the engine is pretty much bein turned over by the wheels with barely any fuel being injected, if you coast out of gear the engine has to inject more fuel to turn the engine over itself, sitting with the engine running for 3 minutes is roughly 1 miles worth of fuel, i didn't believe it till i tried and it makes a big difference, my mk2 escort with a 1660 xflow lump on bike carbs returns 44 mpg on motorways with a 4 speed box.