With a 5-mile commute on a 30-degree day,you'll only see about 73% of Summer city mpg.It takes 22-miles of continuous 50 mph driving to fully warm a car to its top equilibrium mpg,regardless of temp.
So your short drive is eating your lunch!
And it will be very hard to see benefits from mods unless you do a 22-mile pre-warming drive firsthand.
