It would be really good if one of our board members happened to live nearby and would take a test drive with you. You'd get a much better indication than anything we can estimate here. But if that doesn't happen, I'd look at it this way....
If you have 70 mile trip, plan for 75 so you have a little margin.
I estimate battery capacity at 18.5 kWh (although others may have slightly different estimates)
So to make it, you would need to maintain 18.5/75 = 246 Wh/mile. This is a reasonably achievable value, even at freeway speeds.
But what if you need to heat the car? In extreme cold, heater can consume 6 kW, but let's assume only 2 kW. Assume one hour commute, so you use 2 kWh in the heater, have 16.5 left for travel.
Then you need to maintain 16.5/75 = 220 wH/mile. This is getting pretty good, need to be careful to achieve this.
Plus what if you want to go for lunch? to the bank?.
If it's REALLY cold and you need to run the heater at 4 kW, you have only 14.5 kWh left, and you need to maintain 14.5/75 = 193 kWh/mile. That's not so easy....
It CAN be done, that's for sure, especially in mild weather. But you will need to be careful. If you have a backup car for bad weather, that would help a lot. If there is reasonable backup charging along the way, that would be a huge benefit.
2013 FFE Returned after 3 years with 52,000 miles and battery down to 15.2 kWh
2014 Volt returned with 43,000 miles
2014 Volt 26,000 miles
1967 Corvette 427
1962 Corvette 327
Awaiting a Bolt