I'd normally unreservedly concur with the recommendation to lease, given potential temperature issues in Sacramento, but having never done a lease I'd say it would depend on whether you can get one with a sufficiently high mileage allocation, and what that might cost. Allowing for vacations and holidays, if you use your car just for commuting the equivalent of 48 weeks/year, you'll be putting on 17,280 miles/year or 1,440/month. Realistically, you'll also be using the car for local errands and trips too. So a 12,000 or even 15,000 mile/year allocation isn't going to cut it, if you're paying $0.20/mile overage fee. You'd probably want a lease with at least 20k miles/year if you can get it, and you'd need to see what the residual value was and whether it was cheaper to just buy the car and keep it until it's no longer of any use to you.
Second, before you lock into a Leaf you should also consider whether any of the other available EVs might be more suitable for you. While Sacramento isn't Phoenix, it does get hot in summer and I won't be too surprised if we start to see central valley Leafs showing accelerated battery degradation ala Phoenix by the end of their second summer. You should probably also consider the Ford Focus EV (FFE), Honda Fit EV (HFE), Plug-in-Prius (PiP) and the Volt. Assuming this is primarily a commute car (you didn't mention whether this was going to be your sole car), any of these can work for you. You can read something about them in the appropriate topics of this sub-forum:
http://www.mynissanleaf.com/viewforum.php?f=10" onclick="window.open(this.href);return false;
To summarize, the FFE and Volt both use active, liquid-cooled Thermal Management systems (TMS), which will slow the heat-related accelerated degradation which is causing the problems in Az. and Texas. In addition, the TMS will prevent these cars from temporarily losing battery capacity in winter owing to cold (the battery is heated or cooled as necessary when the cars are plugged in), minimizing their variation in range from one season to the next. Sacramento morning commute temps are often sub-freezing, so this can definitely be a factor. With the Volt it really doesn't matter that much, as the gas engine will make up the difference if necessary.
The HFE is only available for lease, but it has the best efficiency and range on the EPA mileage cycle of any of the affordable* BEVs, 82 miles versus 76 for the FFE and 73 for the Leaf. Its active TMS is air-cooled instead of liquid-cooled and it also uses a different battery chemistry from the others, so it's unknown how well it will respond to high temps. Because it has the smallest battery with the best range, you will get more range back for each hour you charge at work, and won't need to charge as much in any case. However, neither the Fit or Focus are currently available with an L3 charging option, which isn't a problem in the Sacramento area at the moment but may well be in the future.
Given your range requirements I'd say the Volt would be a better choice than the PiP, as you can almost certainly make the trip into work on the battery, and most or all of the return trip (assuming you charge at work). The 2013 Volt will have a slightly improved battery that boosts the EPA range from 35 to 38 miles. If you do go for the Volt, unless there's some options on the 2013 that you really want and can't get on the 2012, it's probably not worth waiting, as GM is offering good deals on the 2012s now.
There's also little need to install L2 charging at home with either of the PHEVs, which will typically save you $500-2,500 depending on how much work is required and how much you pay for the charger. And if this is going to be your only car, you aren't going to be able to run up to Lake Tahoe for the day or weekend in one of the BEVs easily, anytime soon.
Finally, if you do decide on a Leaf and aren't sure whether to go with a 2012 or wait for the 2013, the 6.6 kW charger of the 2013 shouldn't be a significant advantage for commuting, but may be for general utility. If leather seats are a big deal for you you'll have to wait for the 2013s.
The big question mark is whether the new heater will be sufficiently more efficient in the temperature range you're going to be experiencing to be worth waiting for (note, using heat and defrost cuts the range down far more than using A/C). Heat pumps are definitely more efficient in moderate temps than the Leaf's current heater, but we don't know enough about the specs of the new heater to say whether that will be the case in your temps. You will undoubtedly be able to get a better deal on the 2012s as Nissan tries to clear them out (and sales have sunk owing to high-temp worries).
Anyway, more food for thought. HTH.
*I'm defining affordable as a base model MSRP of <$40k, before options or incentives.
(yes, it's hard to believe, but trust me/us on this.) And I doubt the diamond lane in this area allows 75mph (this isn't LA) ... what route are you taking currently (i.e. what's your starting point) ? Yes, the gas savings will be HUGE and could pay for the discounted LEAF. The savings on the EVSE are nice too, although that is not a time factor (the gas savings is -- starting next week).
