Leasing is a horrible option on a per mile basis. Would be better to just pay the tax credit amount toward the downpayment (and re-collect it later) to lower your monthly payment. Then again - if you're concerned about the monthly payment, you probably don't want to buy a new car.
Leasing can be a great way to drive an EV, and then to buy it if it works out, but the lease structure has to support that. GMAC clearly wants the cars they lease back. In the case of the two Priuses we'e leased, though, we could have bought the cars for the residual - and did with one - for little or nothing more, total, than buying them new.