Trace amounts of white smoke out the exhaust

Since the problem seems to be pretty consistent, your engine seems to be in good shape, and the weather has been cold, I'm wondering if you are having a problem with water in the fuel. If so, there are two possible sources; condensation in the fuel tank and/or condensation in the fuel at the station where you are buying fuel for the car. Remember that ethanol is hydrophilic (attracts moisture). Try a treatment of "dry gas" additive in the car and see if that doesn't reduce the problem.