as per
http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=33900-
"When fully charged, this vehicle can go about 38 miles on electricity alone, costing you about 4.1¢ per mile.
After the first 38 miles, the vehicle will function like a regular hybrid and consume only gasoline, costing about 10.8¢/mile."
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I am quoting averages. If you are an uber economic driver we cannot transpose that to someone else. It is however irrelevant your numbers don't work for him either. The point was that the cost of the vehicle compared to the cost savings for the OP is not worth it at this point in time.
This will change in the next few years, so considering the OP does not want debt, and really loves his truck the best course of action is to:
1 - sell the civic since there is no love for it and it's not saving much money
2 - save money while investing and gaining interest for the next few years
3 - purchase a high MPG car (maybe electric, maybe PHEV - who knows what will happen in 4 years) cash when enough is saved if the commute continues. I have high hopes in the Tesla model "E" and their contributions to the automotive field
4 - keep the truck forever. No sense in ditching it now, there is much love for it and the cost savings would be negligible.