As far as I'm concerned economy mode is a pain. My wife was driving our 406 on Saturday when it broke down on her. The AA diagnosed a crankshaft sensor. However while she was parked with the hazard warning lights operating the economy mode cut in and that stopped the hazards working. As far as I know there are only 2 ways to get out of economy mode. 1: By starting the engine which obviously won't work if car has broken down. 2: Disconnect battery and that resets everything including radio presets.
Hope this is of help.
Ron
Ron, March 2008