It has become clear that Nissan has put a fairly large number of Leaf SV cars into circulation without the (new for 2018) "Cold Weather Package." This is very unfortunate, and it's something that prospective Leaf buyers and lessees need to understand. First, a little backstory:
Before 2018, all Leaf SV and SL cars made from 2013 on were equipped with a so-called "hybrid heating system," consisting of both the resistance heater found in the Leaf S, and a very efficient, energy-saving heat pump. This heating system, along with the front (and often rear) seat warmers and steering wheel warmer, greatly improves the range of these cars in Winter weather that is above, and even slightly below, Freezing (32F/0C). Below the mid to low twenties Fahrenheit the advantage becomes minimal, but since most Winter driving in the US happens at more moderate temperatures, this has been a real advantage for all Winter drivers of later SV and SL leafs. Until 2018...
When Nissan decided to cut costs as much as possible on the 2018 Leaf, in order to maintain the same MSRP for each model, they did it in two ways. First, they reused as much of the first generation Leaf structure, interior and drivetrain as they could. Great, no problem. Second (and this has gotten much less attention, unfortunately), they stopped equipping the SV cars with a standard heatpump, heated seats, or even heated steering wheel. The 2018 base SV is now essentially a Leaf S with an infotainment system, telematics (remote access) and alloy wheels. In order to get the heat pump - or even seat and wheel warmers! - you have to order or select a car with the "Cold Weather Package." The S now also comes with no seat or wheel warmers, unless you order the Cold Weather Package (CWP) for that model, which provides those, but with no heat pump.
To make matters worse for drivers in colder climates, Nissan appears to be dumping large numbers of SV cars without the CWP in Northern states, and Nissan dealerships appear to be selling them, in at least some cases, without informing buyers and lessees that they are not getting the very features that make the Leaf superior for Winter driving over most other EVs. In at least one case buyers were apparently told that the 'seat warmers are only needed for the leather seats in the SL' with no mention of the lack of a heat pump.
To sum up, if you live in a locale that experiences Winter, make sure that either the Leaf you buy or lease has the Cold Weather Package, or make very sure that you don't want it. Do NOT rely on Nissan or their affiliated dealerships to help you make an informed choice here, because whenever your interests diverge from theirs (in this case their desire to sell cars not properly equipped for the climate in which they are being offered), they will usually give you the shaft.
On a related, note, if you are looking to drive a 2018 Leaf with the expectation of using it for long trips, with multiple fast charges, think again. A search for "rapidgate" will show you that the 2018 Leaf does not handle multiple QC charges well or quickly.