Based on my experience, absolutely. The coolant goes through the entire module which is pretty long on the M3. You definitely do not want to create too much of a temperature difference between the cells. Equal temperature cross the entire battery is just as important as the temperature itself. For almost 2 years now I have looked at the CAN bus data in realtime checking the battery temperatures for each module and how much it differs going in and going out on my Model S. The highest temperature difference between coolant going in and coming out is maybe 4 degrees C. The motor and inverter can be 80 C or more but the coolant going into the battery is never much different from the cell temperature. So I'm convinced that's by design. Just a real world data point that relates to your calculations. I did a test heating up my battery from about -9 C to 12 C and it took about 35 min and used aprox 3 kWh.