What are you looking for the car to do?
If you are looking for pure driving excitement and thrill I would go with the m3. If you are looking for something that will be more of a DD I would go with either the IS-F or the C63. Between the two the C63 will definitely be more exciting and engaging, and will be a good complement to your m3. I personally don't understand the point of an IS-F; these type of cars are designed to provide the driver with a sense of thrill and excitement, but the IS-F leaves me feeling to detached from the driving experience. I would go with a regular lexus over the IS-F and save some money. Also, why restrict yourself to only these 3?
Last edited by m3dude; 03-12-2013 at 10:56 PM.
Reason: new information about posting noted