Rex: clarification.

I drove an i3 REX for first time today on a thirty mile journey. I was curious to see how noisy the two cylinder petrol engine would be. The engine, cutting in at speeds in excess of 10mph, was acceptably quiet, and was just decernable above the road noise at speeds below 15mph.

There seems to be confusion surrounding the use of REX on long journeys. It is not clear in any BMW info if you can run the engine indefinately, or any effect so doing would have on the performance of the i3. I therefore must assume that performance is reduced somewhat akin to a 'limp home' mode seen in other areas. Anyone know the answer?

Chris

Welcome to the forum.

That's the $3850 question that e-v-e-r-y-o-n-e has be wondering about for a year or two now. We are starting to get the answer this month -- the test drives last week and this week are finally shedding light on the actual REx performance.

Unless BMW puts some sort of clause in the warranty contract about it, I think you can run the car in gas mode as long as you want. Other people will have other opinions. Mine is that you can drive the car for a thousand miles straight if you want, as long as BMW doesn't have any language in their warranty limiting you otherwise.

As I say in my checklist, personally I'm also completely OK with degraded performance in range extender mode, especially if they give my a "hold mode" that I can use to force the gas engine one early and preserve some electric range for the end of the trip, when we drop out of highway cruise.

Chris said:

I drove an i3 REX for first time today on a thirty mile journey. I was curious to see how noisy the two cylinder petrol engine would be. The engine, cutting in at speeds in excess of 10mph, was acceptably quiet, and was just decernable above the road noise at speeds below 15mph.

There seems to be confusion surrounding the use of REX on long journeys. It is not clear in any BMW info if you can run the engine indefinately, or any effect so doing would have on the performance of the i3. I therefore must assume that performance is reduced somewhat akin to a 'limp home' mode seen in other areas. Anyone know the answer?

Chris

Click to expand...

I was at a private i3 event at the LA auto show yesterday and Jacob Harb, the manager of electric vehicle operations for BMW NA said this: "You could drive an i3 REx from New York to LA if you would like to, technically the car is perfectly capable of doing it" The question is would you want to do so having to stop for gas every hour? People are going to find the range extender is more capable than most think. He also brought up the quotes that have been circulating that the REx "Isn't for daily use". He explained that BMW doesn't envision someone with a 110-120 mile daily commute the right fit for an i3 REx. You could do it, the car can definitely drive 120 miles every day, but BMW believes that someone with that kind of daily driving demands may be better suited with another vehicle.

Well, I had a 25 mile Test Drive today here in the San Francisco Bay Area (mostly on Hwy 92 and Interstate 280) in a Solar Orange i3, apparently one of the "US Fleet" that was used at the LA Auto Show.

These cars are a blast to drive and the LA Show cars are COMPLETELY LOADED with options, including full leather, voice management of Navigation functions and Adaptive Cruise Control, which I got to experience (for the first time ever) as we caught up to traffic traveling downhill on a significant grade on Highway 92 with cruise set at 68 mph ==> as we caught up to the cars ahead, the i3 slowed firmly but smoothly down to 63 and kept a constant and significant distance from the car in front. Earlier I had a chance to blast by a 5 series on a two lane road ... Cool! :twisted:

I mentioned to the BMW Rep that the US Rex cars will be constrained by a CARB requirement that eliminates the ability to manage battery status i.e., the "Use Battery Now/Use Later/aka Mountain Mode" of European i3s. I told him that my understanding is that Rex will only start at a quite low battery level (approx. 5% ? ) and will not re-charge the battery but will simply provide a "Keep Going"/"Get Home" mode.

==> He was completely unaware that the US cars will be different in this way. :shock:

When I also mentioned that there has been discussion of a possible "upper speed limit" while in Rex mode, he got really interested in learning more about the US Rex technology and limits. He called me back about an hour later stating that a BMW USA executive had just told him that top speed of US i3s in Rex mode will not be constrained; IOW, 90+ mph. I didn't get into the "Rex Power Required to Maintain X MPH" discussion with him.

EDIT: Apparently, power/speed restrictions were considered in CARB's Draft BEVx regulations but were dropped from the final version.

We'll have to see what speed an i3 in Rex mode can sustain in 15 mph headwind/uphill/cold/max heat or hot/max A/C conditions.

Hope I have the chance next year to try out these scenarios!

Hello, my first post on My BMW i3.com
I am here in Maldon Essex England and would love to own an i3 but would do without the REX.
So I follow closely the arguments for and against the option.
On this site somewhere I saw, if I got it correct, that the REX is not an option available in Norway.
Why would that be?

I will use my i3 for commuting to the office, 95 kms per drive. There are chrgers at the office parking place, 4 in total, but I have to arrive at 7.30 there to find a free one.

RichardG said:

Hello, my first post on My BMW i3.com
I am here in Maldon Essex England and would love to own an i3 but would do without the REX.
So I follow closely the arguments for and against the option.
On this site somewhere I saw, if I got it correct, that the REX is not an option available in Norway.
Why would that be?

Click to expand...

This is pure speculation. I think I've read that the BEV in Norway has the heat pump fitted as standard to help battery performance in their low temperatures but the heat pump cannot be fitted to the REX. If all this is true then it appears BMW have prioritised the compulsory (not the right word but you get the drift) fitting of the heat pump over the option of supplying REX to the Norwegian market.

Bill

In the UK you can have either a REX or BEV with Heat Pump. No option to have the Heat Pump with the REX as it is evidently installed where the REX is!

Bunter said:

RichardG said:

Hello, my first post on My BMW i3.com
I am here in Maldon Essex England and would love to own an i3 but would do without the REX.
So I follow closely the arguments for and against the option.
On this site somewhere I saw, if I got it correct, that the REX is not an option available in Norway.
Why would that be?

Click to expand...

This is pure speculation. I think I've read that the BEV in Norway has the heat pump fitted as standard to help battery performance in their low temperatures but the heat pump cannot be fitted to the REX. If all this is true then it appears BMW have prioritised the compulsory (not the right word but you get the drift) fitting of the heat pump over the option of supplying REX to the Norwegian market.

Bill

Click to expand...

Somewhere else on the forum, this question has been answered by a Norwegian blogger.

It comes down to a tax question there. Only BEV's seem to be eligable for the EV tax breaks. Adding the REx would more than double the catalogue price, so it's an economic driven no go for the REx in Norway.

Besides that, the Norwegian BMW organisation has spec'd all i3's with the heat pump as standard, so there is indeed no room for the REx!

i3me said:

Somewhere else on the forum, this question has been answered by a Norwegian blogger.

It comes down to a tax question there. Only BEV's seem to be eligable for the EV tax breaks. Adding the REx would more than double the catalogue price, so it's an economic driven no go for the REx in Norway.

Besides that, the Norwegian BMW organisation has spec'd all i3's with the heat pump as standard, so there is indeed no room for the REx!

Click to expand...

Thanks for the clarification.

Bill

Heat pump is at the front of the i3 so it's not where the REX engine is. However there could be other 'bits' related to the REX up front (petrol tank/ radiator?) that do get it the way.

See here for details of heating system including heat pump.

http://realoem.com/bmw/partgrp.do?model=1Z22&mospid=56088&hg=64&fg=18

mrsmith said:

Heat pump is at the front of the i3 so it's not where the REX engine is. However there could be other 'bits' relate to the REX (petrol tank/ radiator?) that do get it the way.

Click to expand...

Hi,

cool link to OEM info
My 2cts guess based on the available info is that the heat-pump is indeed occupying some space from where the fuel tank supposedly goes, between the crossmembers behind the front axle.

Regards, Steven

How will the REX pre-condition the battery if the heat pump is not available as an option? And, if indeed it cannot pre-condition the battery, what would the the mileage penalty at, lets say, 25F outside temps?

bxb40 said:

How will the REX pre-condition the battery if the heat pump is not available as an option? And, if indeed it cannot pre-condition the battery, what would the the mileage penalty at, lets say, 25F outside temps?

Click to expand...

I think the pre-conditioning doesn't need the heat pump. At least, I have a REx and it seems to pre-condition. Well, it does *something* when you set it to pre-con - clicks, whirrs and fan noises, at least!

SanSerif said:

bxb40 said:

How will the REX pre-condition the battery if the heat pump is not available as an option? And, if indeed it cannot pre-condition the battery, what would the the mileage penalty at, lets say, 25F outside temps?

Click to expand...

I think the pre-conditioning doesn't need the heat pump. At least, I have a REx and it seems to pre-condition. Well, it does *something* when you set it to pre-con - clicks, whirrs and fan noises, at least!

Click to expand...

Far as I know the two are not related. The pre-condition uses a separate system and it's the same on both variants. The heat pump replaces the interior ?bar? style heating on the non-rex so it uses far less electricity but the piping required in the front for the engine excludes the bits and pieces the heat pump needs.

Didn't explain that well hope it makes sense.

SanSerif said:

bxb40 said:

How will the REX pre-condition the battery if the heat pump is not available as an option? And, if indeed it cannot pre-condition the battery, what would the the mileage penalty at, lets say, 25F outside temps?

Click to expand...

I think the pre-conditioning doesn't need the heat pump. At least, I have a REx and it seems to pre-condition. Well, it does *something* when you set it to pre-con - clicks, whirrs and fan noises, at least!

Click to expand...

Far as I know the two are not related. The pre-condition uses a separate system and it's the same on both variants. The heat pump replaces the interior ?bar? style heating on the non-rex so it uses far less electricity but the piping required in the front for the engine excludes the bits and pieces the heat pump needs.

Didn't explain that well hope it makes sense.