Don't be fooled by the marketing. It's only $699/month if you buy the base model ($75,995), put down $6,000 cash up front, live in a state without sales tax, and pay all additional drive-off fees on top. Good luck finding that deal in the real world.
Here are actual numbers from a dealership for an ELR with Luxury and Adaptive Cruise Control packages ($79,685), a 39-month lease, only 10k miles per year, and a 51% residual ($40,639.35). The dealership didn't disclose money factor, but it seems to be 0.00042 (1% APR).
$79,685.00 price
$ 6,412.49 drive-off cash (i.e., out-of-pocket at delivery)
$ 5,575.00 Ally Bank incentive ($1,925 less than the $7,500 tax credit)
$ ++628.00 government fees
$ 3,759.33 total taxes (CA - 9.00%)
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$ ++925.54 monthly payment
The gross cap cost for this deal is $80,480; the net cap cost is $71,905. The base payment (before tax) is $849.12, and then $76.42 in CA (Los Angeles) sales tax is added.
The drive-off cash includes the first month's lease payment ($925.54), upfront sales tax ($778.95), first year fees ($628), the down payment ($4,000), and "other" ($80).
Total out-of-pocket cost for this lease will be $36,096.06 for monthly payments + $6,412.49 drive-off for a total of $42,508.55. So for about half the cost of the car, you get to drive it for 3 1/4 years.
That seems like a very expensive lease. My payment on my MS isn't much more than that...