Reasons To Opt For REx On BMW i3

OCT 20 2014 BY STAFF 19

Buyers of BMW’s new i3 have a decision to make, whether to opt for the range extender or keep the pure-electric drive of the regular i3. And that decision should be made with an understanding of how you currently drive (not necessarily what you drive).

I have never given great thought towards achieving the most fuel efficient operation of a vehicle. I’ve never really owned any ‘gas guzzlers’ either though, so fuel economy has always been decent even when I’ve exposed my inner hoon.

But there’s always been a gas station nearby. The occasions I’ve run out of fuel have been because of my negligence, not a lack of a gas station nearby. There have only been a couple of times that I’ve planned fuel stops to ensure I wouldn’t be stranded, and that has been in the American west.

*Editor’s Note: This post appears on BMWBLOG. Check it out here.

Tom Moloughney's BMW i3 REx

Tom Moloughney’s BMW i3 REx

And that planning was because there are areas in the American west where gas stations are few and far between. Kind of like the situation is for fast charging (or any charging) stations for that matter. And this is one reason that a range extender makes a lot of sense.

If you can imagine the first automobile trip in the late 1800s, there were no gas stations to fill up at. You had to stop at drug stores and hope they stocked ‘benzene’ (a solvent/cleaner in those days). Otherwise you were stranded. It was a chicken and egg problem. You needed demand for benzene to make it readily available, and you needed readily available benzene to create the demand for it. Of course, benzene is also known as gasoline.

So until we get to the point where charging facilities are as ubiquitous as Quick Trips, the range extender may be the way to go – unless you are coming from previous electric automotive experience.

And that raises another question – given the increased wait time for ‘refueling’ for electrics, would there be a different approach than the convenience-store/gas-station? Juice bar? Internet lounge? Restaurant? Is it time to resurrect the Harvey Houses?

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19 Comments on "Reasons To Opt For REx On BMW i3"

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I only saw one “reason” in the article.. I could come up with many, many more.

“Of course, benzene is also known as gasoline.”

No it’s not. Benzene is not gasoline, but it is one of many components that make up gasoline.

Unless you speak German. Benzin is the term for gasoline. Of course if you want to say Benzene then the term is Benzol.

It’s like saying: “Of course, soda is also known as water.”

The reference to Harvey Houses reminded me of Woolworth’s department stores. I miss those stores and their tasty hot fudge sundaes.

We have to find a way to make fast charging less ‘Orwellian’, and more ‘Rockwelian’ 😉

Free root beer floats while waiting to charge for free at a Tesla supercharger?


Hell yeah!! Best ev idea ever!

The BMW i3 is the better choice. If you’re considering an electric vehicle with a range extender, you will be better off going with the Chevy Volt. My opinion is based on what I have read in Consumer Report and from many reviews of the BMW i3 Rex on the Internet. When it comes to the BMW i3 Rex, buyers beware! The BMW i3 Rex have some serious safety issues.

If you don’t absolutely need the added range for your daily commute and have access to another car for long trips then the i3 BEV is a better choice. You save $3,850, you get noticeably better acceleration, more all-electric range, more efficiency, the same tires front and back so they can be rotated, and in California you get a white carpool sticker. Judging by the BMW i3 forum, you also have far fewer issues if you don’t opt for the REx until BMW works all the bugs out.

That being said, I’m really impressed with the concept of a tiny range extender with just enough power for sustained highway cruising. The software on the US version does cause problems when climbing steep hills after the battery is depleted, but BMW has announced a software upgrade to deal with this.

REX, is Not King!

The gas tank capacity of a “small” Honda generator, e.g.Honda 3000is, is 3.4 gallons.
The gas tank capacity of the BMW i3 is 1.9 gallons.

Wake up ! This is a $4,000 joke.
At your expense, all for the benefit of BMW.

The i3 Rex is actually more efficient than the i3 once you consider the fuel efficiency of your backup ICE vehicle. If you go on a 100 mile trip in an i3 Rex, 80 of those miles are electric. If you go on a 100 mile trip in an i3 without Rex, 0 miles are electric. The non-Rex might be a hair more efficient in EVA mode, but it would take thousands of miles to make up the difference in efficiency from having to drive 100 miles entirely on gas. For the same reason, the Volt is more efficient than the Leaf for many drivers. So chalk up “more efficient” as another reason to buy the Rex.

“The i3 Rex is actually more efficient than the i3 once you consider the fuel efficiency of your backup ICE vehicle.”

We just sold our backup ICE vehicle on craigslist last week. A Model S is our road trip car and the i3 BEV is my wife’s commuter car. So at least in our case, the i3 BEV is more efficient than the i3 REx in all situations.

I’ll admit the Model S cost a bit more than the $3,850 we saved by choosing the i3 BEV over the i3 REx and it would be harder to not have an ICE vehicle in parts of the country with fewer Tesla superchargers. But so far it has worked great for us.

Yup, if your backup car is a Tesla, then you’re the exception. 🙂

I see the range extender as a $4000 insurance policy against getting stranded. It’s not meant to allow road tripping. How could it with a tank smaller than 2 gallons. It’s meant to give you comfort on an 80 mile trip in a car with 80 miles of range.on the other hand you could hire a tow truck quite a few times for that money, wasted time aside.

Not Exactly!

There is now a 330lb passenger in the back seat who travels with you wherever you go.
Your acceleration goes from 7.2 to 7.9,
your range is no longer 80mi, it is reduced to 72.
This is about to get worse. BMW is about to fix the dangerous Rex power reduction which is causing freightening “Passing Problems.” They will do this by retaining a larger percentage of the batteries charge, to boost the Rex’s performance, a temporary fix at best! This hold back, of energy stored in the battery, will reduce your 72 mile electric range even more.
Oh, and Winter is coming !

You think winter supports your point?!?

Winter is a MAJOR reason to choose the REX. The pure EV can lose enough range to make 60 mile round trips impossible in cold weather. It’s not just about temperature, as headwinds can be brutal on range, and slush/snow also increases rolling resistance.

The REx has some compromises, but as mentioned above, if it saves you from needing a backup car, it’s well worth the price tag and weight penalty.

I think they will be vital to mass adoption of low cost EVs. Eventually range extenders will be $2k options, have 5+ gallon tanks (when CARB credits become less valuable), and may possibly improve performance.

Yes !!!

My point is,,,,,The i3, in all areas including range, fails to offer any improvement over other existing EVs.
It is only Over Priced, Not over engineered.

In Winter the i3 becomes even more Obvious deficient !!

I just said the i3 is not “over engineered.”
That is not true.

In fact, my most profound Disappointment is that the i3, has been over engineered for BMW’s bottom line, with economies that have made everything about the car, Cheap.
“The Emperor Has No Clothes”
Now BMW is spending millions of advertising dollars, that e.g. could have bought larger batteries,, to make you believe, You should have one and at a premium price.