Unless you want the AS4s, depending on how much you drive, my electricity is so expensive in California that my estimate shows that the OEM MXM are less total cost of ownership, even though they cost more to buy....
Math:
Cost of AS4 at Costco: $900.82 installed
Cost of MXM4 at Costco : $1,164.92 installed
Cost difference : $264.10
MXM4 efficiency (including charging losses): 0.3 kWh/mi
AS4 efficiency (including charging losses): 0.36 kWh/mi [assumes 20% worse]
Cost per KWh: $0.22 off-peak
Miles per year: 12,000 miles
MXM4
12,000 miles/year * 0.3 kWh/mi = 3,600 kWh/year
3,600 kWh/year * $0.22/ kWh = $792 year in energy
AS4
12,000 miles/year * 0.36 kWh/mi = 4,320 kWh/year
4,320 kWh/year * $0.22/ kWh = $950 year in energy
$950 - $792 = $158 savings/year
$264.10 / $158 = 1.7 years to start saving with MXM4...
No doubt, someone who drives less and has more affordable electricity might break even or even be cheaper, but not for me. For me, TCO is clearly with MXM4