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So we are having problems with our c240. The car wont start up so I think that is dealing with a need for a new battery. But when driving the car will not allow you to drive past 60 mph. I have noticed that the car has been shaking engine wise lately and think it may be because of bad spark plugs. I dont see why the battery would cause the car not to go past 60mph. Does anyone know why this is happening and what I may need and how much it may cost? thanks is advance