I have a 2011 with 12 bars (new lizard battery installed March '15) and drive a mix of city and highway. Over the last 12 months my miles/kwh has averaged 4.0. It goes up in shoulder and summer seasons (approx 4.2) and drops in winter (with heater use, I estimate around 3.7). I drive smoothly and almost exclusively use regenerative braking, but I also drive at 75 where the limit is 75 (some others on the forum will stick to 55 for efficiency) and my tires are only at 34PSI (others have them at 40 for efficiency). You could definitely drive more efficiently than me if you needed to, but I should be a reasonable benchmark for real world driving.
Making the assumption of 4.0 miles/kWh, you would require 60/4=15kWh just to make your commute. Nameplate battery capacity is 24kWh, but even a brand new battery only has usable capacity of around 22kWh. An 11 bar would be around 80% of this, so 17.6kWh. 17.6-15 = 2.6kWh which may or may not be too close depending on your tolerance for range anxiety. Moderate heater use in the 2012 (this has a resistive heater) could easily average 2kW which will consume 2kWh per hour of driving. This would push you down to almost zero margin.
In extreme cold the battery capacity is reduced a little (I am unsure of percentages). This cold effect is not permanent, and you can minimize it by timing charging to end just before you leave. Do you need to drive in snow? This apparently requires more energy due to overcoming snow friction (not something I experience in Dallas).
Is your commute flat or up/downhill. If there are elevation changes, do you initially start driving uphill or downhill when you leave your home? Is the start of your trip city or highway driving? If highway, is it in traffic or free-flowing? Regeneration is heavily limited when the battery is full, so if the start of your commute is downhill, city or stop & go traffic you will be using friction braking, which will burn a couple of miles of range.
You seem to be right on the limits of the range sweet spot. If you can eek out your commute you will get awesome gas savings. Some options to make this more comfortable for you:
-Consider a 2016 SV or SL with 30kW battery.
-Consider a 2013+ SL or SV car (which has the much more efficient heat pump heater). You would want a 12 bar (min 85% battery capacity).
-Can you get L1 (120V) charging at work for a couple of hours, particularly in the winter? Maybe check with the maintenance guy if they have any service receptacles anywhere near a carpark.
-Is there a L3 (DCQC) charging station on the commute home in case you need to grab a couple of minutes charge in case of emergencies or perhaps on extremely cold days?
I assume you've become familiar with leafspy from reading this forum?
Good luck. Feel free to ask as many questions as you need. The leaf is a great car, but I'd hate for you to suffer range anxiety it if doesn't meet your needs. Perhaps rent one for a couple of days (there are a few on Turo if you are in Denver, see https://turo.com/rentals/cars/co/aurora/nissan-leaf/230125) and test drive the route.