I've had my C-MAX for a week and I've already replaced a bunch lights from incandescent to LED. I don't know i you guys know about LED ghosting, but when the LEDs are supposed to be off, there is still a tiny bit of current left in the circuit to cause the LED to glow very faintly. I just ran into this with my licence plate lights and my high mount center brake light. Might be happening with others, but I haven't been looking that hard.
I used 194 LEDs from Diode Dynamics, the HP5 (brighter) version for the center brake light, the puddle light and signal light in the mirror and I used the HP3 (dimmer) version for the licence plate lights. When it was darker outside, as soon as I unlock the car, the parking lights come on and I saw a couple of the LEDs in the center brake light start to faintly glow and flicker. After I lock the car, they would continue to do this for quite a while. I learned that putting a 1K ohm resistor in parallel with the LED bulb will prevent this phenomenon. It allows the trace amount of current and alternate path, preventing the LEDs from glowing and flickering.
In the attached picture is where I put the resistor for my center brake light. No more flicker/glow!
I just shoved the resistor in friction fit for now. It was threatening to rain on me when I was doing this. I'll secure the resistors better, but it solved the issue.