hawke94

My wife says when she starts the car at the end of the day (around 10:30pm), the car shudders for a 1-2 seconds and then all is normal. I tried this last night and I think I felt some mild vibration in the steering wheel for about 1 second. She's noticed this since last week.

The car is a 2013 C300 in Massachusetts with 30k miles. It sits outside in the open air parking lot from 4pm- 10:30 pm. The day time temperature here has been hot and humid during the day, 85-90F. At night, the temperature is around 70F when she goes home, so not very cold at all. The car drives normal afterwards starting with no loss of power or anything else. It's normal if you shut off and restart the engine. It also never happens when she starts the car in the morning in our garage at 8:00am. The dealership has looked the car over but can't find anything wrong nor can they reproduce the problem. I've heard of rough cold startups but not when the car is still warm.

Any insights would be greatly appreciated!