If you are really doing 10-100 miles a week at less than 40+ mph a 500e charged once a week might work out. We could get about 109 miles of sub-40mph driving in ideal spring weather. In the winter with the heater on knock off about 40% (though using the seat heaters is a great alternative) and in the summer with the AC on knock off about 15%. The 500e will do 40a charging, so you can fully charge one in four hours with a regular Level II charger. Note that's 24 hours with a 120v/15a Level I.
Although inexpensive operation and maintenance is a big plus, you're probably talking $12k for a nice used '13 500e vs. $5k for a nice used 500. $7k buys a lot of gas.
Do expect typical Italian/Chrysler quality control. Don't expect $0 in maintenance. My bet is that mile for mile, it's still cheaper than a Smart.
Have you considered something truly wretched like a Mirage?
https://sfbay.craigslist.org/eby/cto/6156744833.html
or iQ
https://sfbay.craigslist.org/sfc/cto/6133918912.html
I think I'd still lean towards the Fiat - it's probably safer and probably more fun to drive. Maybe not more reliable.