[kaisen]

Even if superchargers weren't "free" and you were charging your Tesla S 85kWh at home each night, it would still be ridiculously cheap. SoCalEdison has an off-peak charge rate for EVs at $0.08 per kWh and the Tesla Model S 85kWh is rated at 37 kWh/100 miles.

So if you drove 1,250 miles per month (15K/yr) and charged at home every night, you'd have used 463 kWh at $0.08 per, for a total monthly electric rate of $37.00..... yep, thirty seven bucks a month to drive your Tesla if you paid for every bit of electricity.

Compare that to a gasoline powered car like a Honda Accord 4 cylinder at 3.0 gals / 100 miles (33mpg EPA combined) and $4.10/gal (actual CA avg right now) for that same 1,250 miles would be $154.00

$154.00 - $37.00 = $117 per month energy savings ....... or save $154/mo if you use Tesla's free superchargers

That's SoCal pricing. Savings would be even greater in some parts of the country (in Minneapolis the off-peak EV rate is $0.035/kWh)