I've got nearly 20,000 miles on mine. One thing I just discovered is that the tires, 21" super-soft compound high-performance Michelins, only last 20,000 miles and cost $2900 to replace. This works out to $0.145 / mile, which is 3x more per mile than electricity costs me. And about what you would spend on gas for a 25 MPG car.
I didn't really buy it for the savings, though.