5stringJeff said:
In about 10 years, electric cars with comparable ranges and performance will be half the price, I'm sure. So, a quick cost analysis:
A car that doesn't require gas saves you having to fill up. If one assumes that one drives 15,000 miles a year and gets 20 MPG, they'll use 750 gallons of gas. At $3/gal, that's $2,250 each year in gas. If you own a car for 5 years, that's $11,250 spent on gas. Of course, there's other costs you'll lose out on, like oil changes, but some additional costs, namely your electric bill. But let's assume that those cancel each other out. So, it would be cost effective to purchase the car if it were up to $11,250 more than a comparable gas-powered car. The average new car costs about $22,000 (depending on body style, features, etc.), so when comparable electric-only cars fall in price to about $33,000 (again, depending on features), they will be economical to buy.
The cost of electricity right now is generally $.75~$1 equivalent. So, $3750 in your example. That's still a nice $7500 difference over five years.
But the difference in maintence costs is potentially huge. In your example, you are assuming 15k miles per year. So that's 5 oil changes at...$30 a pop? It's been a long time since I paid for oil changes, so I don't know. That would be $750 over 5 years. No air filters to change, so that's more money saved. Your car note might be $100 a month higher, but your associated costs could easily be $150 a month lower, almost immediately.
As the car grows older, the electric can potentially have far fewer repairs. An electric car may have a transmission, but it's not an absolute necessity. Mitsubishi will be building electric cars with
in-wheel motors. So no more transmission flushes and no clutch replacements. No differential fluids either. You can make an AWD car without a transfer case, 2 differentials, and all the maintence headaches. If a motor goes out, you can keep on driving. Go to the dealer, and he can swap out the bad motor by simply unbolting the wheel and unplugging the motor. And motors can be rebuilt with much greater ease than engines.
And since we've got four electric motors, we don't even really need mechanical brakes--no more brake pads and rotors, and no more brake fluid changes. (Actually most proposed EV's still have brakes, but with regenerative braking, you'd use them less.) No more power steering fluid changes, because an electric car will almost certainly use a motor for power steering. Really, your only maintence items would be tires, alignment, A/C, and shocks. Oh yeah and let's not forget: instantly hot heaters!
This is assuming that the newest batteries coming out will be as long-lived as they say. The Tesla will need a new pack at 100k miles, and it won't be cheap. Newer battery tech will last for decades. I can imagine carmakers adopting 10 year warranties as standard.
And then there will be the performance benefits. Batteries will be spread out along the floorpan or along the backbone of the car. Motors are smaller and more compact than engines. EV's will have an incredibly low center of gravity, for
awesome handling. Plus the ease of having (or adding later on, if you want) AWD. The Tesla roadster is only the beginning of what's possible with better batteries. EV's will beat the pants off today's supercars, without the huge maintence bills. They will also have far greater flexibility in designing the body style, without a bulky engine and transmission to work around. A Miata-sized car could probably have room for four people.
"power up the engines! Warp 3!" 
