I wanted to get into an EV last year, but had a limited budget. I purchased a 2016 REX with 7,800 Miles, it was off a 2 year lease from a dealer. $20,700 with 5 Year CPO unlimited miles. My daily commute is 72 miles each way. I installed level-2 charger at home and have access to level-2 charger at work and now a 50kW DCFC around the halfway mark - Opened in June of this year. I purchased the car 7/28/2018 as I said about 7,800 miles - I now have 52,000 miles. My REX died at 36,000 - Dealer replaced the whole REX unit and generator - I believe this to be a very rare issue -the crank in the rex engine cracked. Since then all good. In the winter I have to use the REX for approximately 30-45 miles out of my total 144 round trip commute. My longest trip to date is 1,400 miles round trip. No issue, just a lot of REX stops since there were very few Level-2 chargers along the way and no DCFC. DCFC is a game changer, hope to see more soon. You will need to code the i3 - very easy with BimmerCode and a $20 adapter. Need to make fuel take capacity reflect the max capacity which will give you more REX range and enable the ability to manually turn on REX below 75% battery. The REX will hold state of charge at highway speeds under 65 MPH. Above that you will see the battery slowly drain. I have no issues with REX other than I am burning gasoline. If you live in a snow-belt area, consider snow tires. No issues last winter in heavy snow with 4 snow tires. REX can be loud at times but radio covers it up. My Cons: Tires - they tend to attract nails like a magnet and they wear out around 20K miles, base radio is garbage, no heated steering wheel, no apple CarPlay (available now on newer models, but BMW charges and annual fee to use), halogen headlights (just ordered LED bulbs).
It's been a year and a half for me and an still absolutely love driving the i3. Would like a 2019 with the extra range.