(from the article):
"But those potential i3 owners need to understand a critical point: The BMW i3 may not operate like a Chevy Volt. That is, its performance in range-extending mode may be more limited than when it is running on battery power. One of the core principles behind the design of the Volt was that its performance should be identical whether in battery-powered or range-extending mode.
BMW says the range extender of the i3, on the other hand, is designed not for long-distance travel but purely as a short-term stopgap to get drivers to the next recharging location."
In actuality, its a 650cc engine derived from a BMW Motorcycle, I'm sure it's not rated for continual use even though here in the U.S. some may compare it to a Volt which touts its 'unlimited' range due to the onboard gas 'generator' engine.
Interestingly enough -- another municipality (IL EPA) would put this in the same class as a Volt because the 'engine' is actually a generator and not your typical ICE with a battery pack added (like a Ford C-Max Energi or Prius Plug-In) --- in the i3 application, you would use the extended range gas very sparingly --- I would wonder if they would also have a system that advises that you run it like the Volt so the fuel doesn't get stale after running for long periods of time on electric only.