This is highly dependent on your electricity rate, driving style, and weather - but I've got 376 miles on my Performance. I've used 137kWh to charge over that distance (I've been enjoying it since I picked it up...).
1500 / 376 = 3.98
3.98 x 137 = 545.26kWh projected over 1,500 miles
My electricity is 12 cents/kWh, so my projected cost is $65.43 over 1500 miles. That's 4 cents (or .36kWh) per mile. There are multiple rate plans with most electric companies, so check to see what makes the most sense, and if there are off-peak times, make sure you set charging to that window.