Our S reg A class Elegance 1.8 semi automatic has lost power totally a few times in standing water (not flood) road conditions, so that the accelerator simply stops driving the car. This has previously happened when the car was moving off eg from a queue at a roundabout, and was merely inconvenient. A dealer seemed to know about the problem when phoned, and said the solution was simply to switch off the engine and re-start. This has worked in the past. However the problem hasn't gone away and the other day the same problem happened to my wife, potentially much more dangerously, at 70mph in the fast lane of the M11, again with heavy rain and some standing water. After a spell on the hard shoulder, it restarted. Any ideas as to the problem, how common it is and the cure?