Looks like a fuel problem if the sparks are present. Check the coolant temp sensor. This sensor informs the ECU and ICU about the temp of the engine, if for some reason the ICU thinks that the engine is warm when it is really cold, the car will not start. This is the last sensor on the engine, towards the windshield. The resistance across the terminals should be between 2.5 and 3.5K when the engine is cold. Try connecting 10K across the wire connector terminals and see if the car starts.

Check the cold start valve. This valve should get close to 12V when you try to crank the car. If you get 12V when trying to start, check that the valve sprays some gas. If there is no gas, then the cold start valve is bad. If you dont get 12V when cranking, then your fuel pump relay is not sending the signal. I think, at one point MB updated their fuel pump relay to activate the cold start relay at a much higher temperature, maybe your relay is an older relay.

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Saumil S. Patel