My wife's Merc has suddenly stopped. she was driving along, when she said she had heard a hissing sound, then the car came to a halt. On trying to restart the car, it just makes a spinning sound, like the starter is turning, but not the engine, the engine wont turnover at all.
Any ideas what could be wrong?
it is a 2002 avantgarde model

Only thing to do is, give the car to me!!! Seriously, it sounds like this is an older Mercedes. The hissing might just be an exploded or punctured fuel hose. Should this happen, obviously there is no fuel pressure and you go NOWHERE. I find it hard to believe that the engine and starter have divorced themselves. If you hear the starter, the engine is usually turning with it. Unless the Bendix gear has failed. The other possibility is that your ignition just decided to die and stop firing plugs. Might be a bad coil. You go NOWHERE. You will probably need to have the car towed to a shop and have these things looked after. Could also be a vacuum line on manifold that jumped out of place. You go NOWHERE.What year and model and mileage?????

Transmission. Hissing sound. Oil pressure dropped. Oil leaked out of transmission and siezed/broke gears.

To transmission can cost 3k

Do it your self from used trans or junkyard can cost under a grand