Madari - what is your plan for this car? Long term ownership, or a quick two to three years until something better (and it will) comes out? If long term, then buy. If short term, lease. Keep in mind the 2018 has a bigger battery than the 2016 and earlier cars.
To do a batteryrun down test, charge the battery to 100%. Reset the trip odometer. Drive the car around until the battery is almost discharged. Park next to a charging station. Roll down the windows and turn the heater on max (the heater uses a lot of battery power). Let it run until the battery is fully discharged. Then read the power used from the trip odometer.
I bought my car new. In retrospect, I probably should have leased it. If I were in the market today, I'd likely be leasing a new Chevy Bollt. Four years ago the FFE was competitive with the rest of the EVs, and was the best price. That is no longer true, as Ford has not kept up with industry in this technology.
PM me if you'd like the name of a good dealer and sales rep that will give you a fair deal if you decide to go with a new FFE.
GONE - 2015 FFE, Magnetic with leather interior, debadged & tinted
38,500 miles (since May 2015), average 246 Wh/mile
REPLACED WITH - 2018 Tesla Model3, LR RWD, Obsidian Black