When i wake up in the morning i cough and clear my through of any phlegm let out a couple of farts then i'm good to go and sound normal. I guess expect your car to do the same..

 

I bought my car used, and when when I first fired it up on a cooler day I was worried if I got a bad engine. I immediately took the car in to the dealership I had bought the car from. They had me listen to the sound of a new car on their lot on startup to compare and I was so relieved (I guess) when it sounded the same. Service rep then mentioned that these 3.7L engines are designed to a certain way to maximize oil circulation on cold start and hence the sound for the initial few seconds.