If the battery is nearly exhausted, it can take 3.5-4 hours to recharge it IF the EVSE they have is capable of outputting the full amount the i3 can use. Not all of them can, and if that's the case, it will be longer. For example, since power=volts*amps, at home, you may have 240vac available and with a 30A EVSE, you'd be close to maxing out the i3's on board charging circuit (max 7400W). Many commercial units may still put out 30A, but their input voltage may tend to be 208vac, or about 13% less energy than your theoretical home unit. My EVSE can output 30A, and my normal input voltage is 245vac, which comes to 30*245=7350W, or essentially all the i3 can take (especially since my voltage is sometimes even higher). Your results may differ.
The small gas tank may mean you have to stop about once an hour depending on how fast you are driving and the roads (hills, etc.). Depending on the speed and load, the REx is a 34Hp max engine, and the i3 has a 170Hp electric motor...it is possible that the REx won't be able to keep up if you're on a long, steep grade at high speed with the heater on max and the lights on listening to your new stereo with the seat heaters on! Cut some energy users, and that may be your speed, and it will just keep trudging along, but get the battery capacity down to a few percent, and the car will start shutting down things on its own, with the last one, how fast you can go. Watch the battery capacity readout, and if it starts dropping too low, slow down and/or shut things off, and you could keep going by filling up the gas tank regularly (way to often for me, but that's personal).
