Considering going from a Leaf to 2014 I3 Rex had a few questions

My fellow leaf members only talk about how unreliable the i3 is. I really want the i3 and just had a few questions.

Limp Mode. How difficult is it for your Rex not to keep your battery charged at 6% going 75mph of higher. going to code asap

How is winter driving? Is it possible with the stock tires. Are the tires different sizes from front and rear

2 carseats in the back manageable

Is 2014 a reliable year, what should I look for in a used i3.

Thanks guys Im really looking forward into getting into one.

Ronmamaci3 said:

Limp Mode. How difficult is it for your Rex not to keep your battery charged at 6% going 75mph of higher. going to code asap

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It's impossible for the REx generator to maintain the battery pack charge above 75 mph because its output is less than the power required to drive that fast. If you code a REx to allow its generator to be turned on manually at higher charge levels, you could drive fast for a significant distance before the charge level dropped so low that propulsive power would be limited (i.e., limp mode).

Ronmamaci3 said:

How is winter driving? Is it possible with the stock tires. Are the tires different sizes from front and rear

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Driving on the stock all-season (19") or summer (20") tires is not safe on snowy roads, but the rear drive wheels carry almost 50% of the car's weight unlike the typical rear wheel drive car, so winter driving with winter tires is reportedly quite good.

If you live where winter tires are necessary, none is available for the optional 20" wheels, so 19" wheels would be better unless you're prepared to buy a set of 19" wheels for winter tires.

All REx models have wider rear wheels and tires than front wheels and tires.

Ronmamaci3 said:

Is 2014 a reliable year, what should I look for in a used i3.

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The 2014 REx model was anicdotally the least reliable. Most of the problems should have been fixed under warranty. However, even 2017 REx's can suffer from diagnostic trouble codes (DTC) that cause the check engine light to illuminate. Many BMW dealers seem to have problems solving the cause of these DTC's.

BEV's seem to be considerably more reliable because most of the problems seem to be related to the REx system. Our 2014 BEV has been to the dealer twice for preventative repairs but has never had a problem that required a service visit.

The REx engine is about 34Hp, and it's running a generator...there will be losses. When was the last time you drove a car with a 34Hp engine? That's why, if you let the battery get way down, it cannot keep up. Drag goes up about at the V-squared rate, so small changes can make a fairly large difference in the power required. The car was designed as a city car, with limited high-speed travel and the REx was designed mostly for a comfort (range anxiety) factor...they really didn't want it there in the first place. It does well for what it is, and yes, people do take them on long trips which is something you'd avoid with a Leaf, since you can just refill the gas tank (about every hour or so).

The REx will turn itself on if you don't use it to circulate the oil, burn the moisture out of things, and verify that it works. It can't do that until your charge is below 75%, because it wants to go through its entire warmup cycle, otherwise, it would leave moisture in the oil and exhaust. That takes about 10-minutes, and it needs somewhere to put that electrical energy it will produce.

There really haven't been many changes, and few that are visible, since the car was originally released. Some of the issues were resolved via software, but there have been a few issues with hardware. As long as the vehicle you decide to buy has had all of its recalls (not many) and service campaigns applied, an older one should be about the same as a newer one. Early on, there were a few hardware things tweaked on the 2014's, but once resolved under warranty, IMHO, they are about the same in reliability, which is pretty good.

If you're going to buy a REx version, you should probably use the REx more than the maintenance cycle would force on you. Many things like it better when you use them, verses having them sit idle for long periods of time.

My benchmarks show 70 mph is the maximum sustain charge speed but your mileage may vary. Going faster and the battery SOC will slowly go down. Go a little slower and once the battery SOC stabilizes, problem solved.

I have a 2014 and a lot of problems were fixed at the factory in the following years.

Bob Wilson