I live on the Gulf coast - slightly cooler summer temps and more humidity than Austin. I bought my 2014 model (w 17,300 miles) back in June and I've only put about 3200 miles on it since then. Overall, my experience parallels what Kiggulak says above. In the warmer months the GOM typically estimates 94-102 miles on a full charge (primarily low speed urban driving). During Dec-Jan, range was typically in the 70s but got down to ~60 on the very few occasions when the temps were below freezing (also got up to the low to mid-90s during warmer spells).
Range takes a hit from the AC but I think the GOM overreacts to it, basically assuming the AC will be running full blast all the time. The real range hit is probably not that bad except for very hot days. The heater OTOH is a real energy hog. One thing to be aware of is that the auto climate control is very aggressive in trying to meet it's temp target. On humid but not so hot days, the temp set point will be reached quickly and the AC will switch back and forth with the heater, wasting energy uselessly. I just switch the AC manually under these conditions. The heated seats are a very nice alternative to the cabin heater and are quite economical.
I will disagree somewhat about the necessity of a level 2 EVSE. If you're only driving 40 mi/day, this will depend on your driving style. Sticking to lower speed city streets, you can probably get down to ~200-220 watt-hours/mile (from battery, not from wall) with some practice. The level 1 EVSE that comes with the car will pull ~1440 watts from a wall outlet and dump energy into the battery at ~1100 watts (75-80% efficiency). So, ~8h of charging could replenish ~40 miles of range if your driving is efficient. If you're not so efficient, you may need 10-12h of charging at level 1. Still level 2 would be very convenient and good to have for emergencies (battery thermal management and cabin pre-conditioning will also work better at level 2). There might also be a risk in relying upon a single device for your charging. If something fries that L1 it could take days to get a replacement. Be sure to check out http://www.plugshare.com - there might be public charging available along your route that you could use in emergencies.
Leaving the car unplugged at triple digit ambient temperatures plus solar gain (no shade) is not going to be good for battery longevity. This is a function of both temperature and state of charge, so depleted battery + high temp is better than full battery + high temp. I would be most concerned about solar gain during high summer. 100 F probably isn't that bad, but add another 25-30 F from baking in direct sunlight all day and you're much worse off IMHO. If you can't plug in, try to reduce solar gain (park in shade, maybe tint the windows). You can also use the MFM app to occasionally remote start the car (~15 min run time IIRC), which should turn on the battery thermal management (which only runs when the car is either on or plugged in).
If you are seriously considering a used FFE, here are a few tips:
1) the 12v lead acid battery might be in bad shape, so have it checked out. This is because dealership people unused to EVs might leave the car unused and unplugged for months on the lot. This is OK for the Li-ion pack but there are constant loads on the 12v that will deplete it. If this happens too many times, it's toast. Note well that even a sick, but fully charged, 12v can still start the FFE just fine, it doesn't take much juice. Mine seemed to be ok for about a month before it became a problem (had lost >90% of its capacity). There was also an issue with the car's software (there is a recall to fix this) that stressed the 12v. If the car you're looking at still has some of the bumper to bumper warranty left, this should cover replacement (if not, there may be some pro rata coverage from a separate battery warranty)
2) there are some necessary recalls for older models: wiring harness, car software patch, door latch, 2G modem replacement
3) insurance may be higher than a comparable ICE vehicle, depending upon your provider.
4) Insist on a long test drive. If you can, do a battery draw down test. If you can't, then at least drive around enough to substantially deplete the battery. The enhanced trip meter will display the energy discharged from the battery and the main display can give you the state of charge. From these you can get a rough estimate of the battery capacity - search the forum. Also, drive it home and plug in with the L1 EVSE to confirm that it's in working order and your outlet can handle it (even if you're installing a level 2, you might need that 120v outlet as a back up).
