REX/ Battery warranties question

Couple questions on the warranties for buying a used i3:

1. What is the 15 year warranty on the REX ":

From the manual:
BMW i3 with Range Extender
The following components and/or systems are
covered under the Federal Emission Warranty for
a period of 15 years or 150,000 miles, whichever
occurs first.
AUXILIARY POWER UNIT (APU)

Does that cover anything that goes wrong with the REX engine for 15 years? Or is it more limited than that? Just wondering if there are potential out-of-pocket repair costs to be aware of if I chose a REX over BEV.

2. Does the 8 year battery warranty on the i3 extend to subsequent owners? I have read somewhere that the battery warranty only extends to 2nd owners if the car is a CPO. Is that true? I haven't found documentation on that, but am wondering if I should only be looking at CPO models.

Thanks!

The components warrantied under the Emission Warranty are only warrantied for repair to meet (failed) emission standards/tests. So, if the State you live in requires the car to be tested as a 'hybrid' and the car fails the emissions test because the REx O2 sensor is faulty and the exhaust reading is outside the emissions test parameters, the emissions warranty will cover the repair to get the car to passing. If the Rex just packs it in, you are on your own.

The 8 year HV battery warranty follows the car, not the owner - and has nothing to do with any CPO warranty. CPO or not CPO, one owner or five owners, the HV battery is factory warrantied for 8 years.

Thanks, that is very helpful!

Have the REX components been pretty reliable? Is there potential for higher repair bills associated with them? Or what costs would I likely be in for on a REX?

I like the idea of a BEV not having any of the ICE components (and also better performance due to weight savings), but I also am concerned about potentially higher resale depreciation on an EV with sub-100 mile range (eg. 1st gen BEVs). So I might just be considering a REX so that I don't have to worry about having an "unsellable" car in a few years.

The things that seem to show up on these forums are more to do with the fuel system than the engine itself. One mentioned more than once is the fuel pump relay needing to be replaced...the part is cheap, plugs in, and most people can do it themselves if they're at least a little handy. Well, once they figure out where it is!

On hybrid vehicles, it seems like they require the fuel tank to be pressurized. That means that it can take a few seconds (longer when it starts to wear out or fails) to relieve the pressure prior to you being able to open the filler. That pressure sensor has shown up as a failure, too. There's no real transmission in the REx...all it does is turn an alternator. Plus, the REx may literally only run in maintenance mode for most users, so that, by itself, can present some problems. IT probably isn't a bad idea to either force it on (by 'coding'), or force it on by running the battery down (not as good!).

If I lived where it rained a lot, or the humidity was high most of the time, I personally, would code the REx and turn it on at least once a month. Let it run until it was thoroughly warmed up, probably at least 10-minutes, and then, disable it unless I had other reasons to run it longer. In stop and go traffic, the REx will usually shut off when stopped at a light, so that should be kept in mind when deciding when and where to do this.

Keep in mind that battery life is more on cycles, so if you can minimize cycles, that should make the battery last longer...now, that's only an issue if you intend to keep the vehicle for a very long time. Using the REx more often, minimizes the battery cycles. Gasoline is lots more expensive than the electricity you get from the wall.

The i3 is actually the most reliable car in the entire BMW line according to JD Powers. The REx engine in the i3 is the BMW 650 scooter engine, which has been around for almost ten years and very reliable. Do some fail? Sure. Expensive? Sure. But out of the 40,000 or so i3 REx cars in the USA, likely less than 0.05% have had a critical REx engine problems, and most will have happened while the car is still under factory warranty. That's less than the statistical chance of being struck by lightning in your life-time.