Someone may want to inform BMW's salespeople about the above, if true. I was told the opposite by a BMW salesperson here in Phoenix. He said that after you drive the full 180 or so miles, you must recharge because the gasoline engine lacks the output to charge the battery and propel the car once the battery has been depleted. He said, "It's not a like a Volt where you can keep on driving just by filling up the gas tank."
So which is it?
AmpedRealtor,
You *can* keep on going by filling up the gas tank.
But there are caveats.
The American version of the BMW i3 is crippled by its American-version software, prohibiting the gas engine'd generator from *recharging* the battery; it only *maintains* the battery's charge at about 6%. The electric car runs off that 6%, and there is enough buffer to allow for short-duration high-demand inputs from the accelerator pedal, such as hill climbs or dusting a Prius.
So it can't recharge the battery from empty to full. The software won't let it.
But it can maintain the battery, and keep on going (and going, and going...) as long as you don't overdo it.
The gas engine is powerful enough for you to drive at 70-75 mph, without depleting that 6%. If you go faster, say 80 mph, the i3 will let you do it (for a while), and the battery charge will dip down to 5%,4%, 3%, to some point where the i3 will cry "Uncle!" and deliberately slow you down, transferring the gas engine's resources from the accelerator pedal to the battery to bring the battery's charge back from the brink of wrack and ruin.
A hypothetical 450 mile trip from Los Angeles to San Francisco will require:
(a) Stopping 5 or 6 times for gas, and
(b) Keeping your speed around 70-75, tops. (This could be difficult. 80 is the new 65 on the I-5).
This hypothetical trip involves the mountainous "Grapevine" just North of Los Angeles, and will require climbing from sea level to over 4,000 ft (~1,300 m), which will rob *any* battery of a good chunk 'o range that you didn't count on. So that first stop may come earlier than you had planned. In the same way the car will slow you down if you are speeding, a long uphill climb may slow you down to 35-40 mph. Hey, the i3's gas engine is only 35-ish horsepower. There are trade-offs here.
Even if you gobbled up all your battery *and* your gas tank and had to gas up in Gorman, the downhill run ought to provide a nice long ride all the way down to the Jan Joaquin Valley on the other side may, through the magic of regenerative braking, recharge the battery by a significant amount.
Bottom Line:
When you are driving off the battery, you have a 170-hp electric motor at your fingertips.
When the battery is empty (okay, 6%), you are using a 35-hp gas engine to run a generator to feed the battery, so you have 170 hp for short blasts, but only 35 hp for the long run (and "long run" is relative when you only have a 1.9 gallon tank).
[Opinion]
It ain't no Model S. But it sure beats whatever's second.
[\Opinion]
-- Ardie