At the moment, the Tesla Model S battery pack is definitely expensive and likely costs consumers about $25,000 for the 85 kWh battery pack. It is likely to last somewhere around 300,000 to 500,000 miles. People are basically paying between $0.05 and $0.08 per mile for it. At a national average of $0.12 per kWh and you get 3 miles/kWh, the electricity cost per mile is about $0.04. With special time of use rates, it is possible to pay for electricity at half that price. Which means $0.02 per mile. That means the cost of electricity + the battery pack = $0.07 to 0.12 per mile.
Assuming super unleaded costs $2.50/gallon, here are some comparisons:
BMW M5, 16 mpg combined, $0.16 per mile.
Jaguar XF, 23 mpg combined, $0.11 per mile
Usually where electricity is expensive, gasoline is also expensive.
Of course, if you are doing this kind of comparison, you are basically removing $25,000 from the price of the car and placing it under the energy/fuel column. So looking at total cost of ownership makes the most sense. Most people aren't yet used to looking at the TCO for a vehicle so electric cars look more expensive up front but if you examine TCO, you'll see that, in many cases, they are less expensive.