to REx or not to REx ?

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psquare

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Call me old fashioned, but I wouldn't mind spending around £3k less on the BEV. It would be our second car, the first one being a 5-seater low-em Diesel.

Daily commute would be 42 miles (both ways combined, also incl 2 school runs), which should leave about 35-40 miles in summer and potentially 18-20 miles in winter. The savings of going for the BEV I was planning to invest partially into the heat pump option.

I've already test driven the REx for a day and liked it, but have got a feeling that we would probably use the REx very rarely.

Am I already answering my own question?

Any pointers welcome!

P
 
Yes, you've answered your own question. For your profile with the i3 as a second car you don't need Rex. Our profile on the other hand has the i3 as the main car (soon to be the only car) with trips which the BEV can't manage at all.
 
Having said that, there will be occasions where we need to drive more than 42 miles a day. This might happen once a week. However for those days, some coordination would be required. Nothing unsurmountable though. In general, I'd expect more car coordination etc to be part and parcel of having an EV. That's at least what I hear from existing EV owners.

With regards to the heat pump: how tangible is the saving in charge for BEV owners with the heat pump? I'd be interested to hear more about that.

Thanks,
P
 
I can't answer to the heat pump question myself, (REx and only had it though mild conditions so far).

But the crucial option, I think, even for REx buyers is DC rapid charge. That's certainly the opinion of lots of Californian owners, and they like us in the UK have the benefit of a growing network of CCS outlets. The REx owners among them say they use DC rapid charge instead of gasoline whenever possible, and keep the REx in reserve for unplanned journeys and for giving them reassurance when a planned journey is marginally within range with battery alone. I haven't had enough experience yet to be really sure, but it feels right to me. If the DC rapid network started costing as much as petrol that might change, I suppose.

We've temporarily gone back to having 2 cars, after 11 years on just one, but we'll soon be down to just the REx i3.
 
Thanks for the link. Excellent post. Funny that he used a similar headline as I did.

Resale value is a good argument, which already thought of. I'm probably in the "pure EV camp" and wouldn't like the complex conversations explaining to people what a REx is, but never mind.

Test driving a Leaf tomorrow for some perspective. Tried to arrange a VW e-Golf test drive, too, but the Dealers in my area are quite clueless. Took 7 (seven) calls to arrange it. Complained and had an apology. As far as that's concerned, BMW has already won.

Thanks for the advice on here.

P
 
Two-car household here. Coming up on six months with the i3 BEV and E90 328i combo. The i3 is the weekday car. We ride downtown together. The E90 is used on weekends mostly. No regrets. Living the with BEV has been much easier than I'd imagined. I'd definitely buy again.

In addition to the purchase price, the REx means slightly slower acceleration due to the weight and added maintenance.
 
FWIW, you can notice the difference in acceleration between the BEV and the REx. I kept my ICE. I drive my i3 most of the time. I liked the lower purchase price, no oil, antifreeze, filter, muffler, etc. maintenance - the BEV basically only needs the cabin air filter and the brake fluid tweaked at 2-years, so almost no maintenance and when it is called for, cheaper. WHere I live, no engine, no emissions testing, and the extra annual cost as well, so my safety inspection is cheaper.

Certainly, if your regular use put you near the limit of the BEV, or it was going to be your only vehicle, the REx may suffice and certainly is cheaper than maintaining two vehicles, but if you can, use the right 'tool' for the job, and the ICE is preferable on a longer trip (I can see 500-miles between fillups on it).
 
psquare said:
Test driving a Leaf tomorrow for some perspective. Tried to arrange a VW e-Golf test drive, too, but the Dealers in my area are quite clueless. Took 7 (seven) calls to arrange it. Complained and had an apology. As far as that's concerned, BMW has already won.
Click to expand...

I agree with jadna that you should have the right car for the job. The i3 is made as the ultimate urban commuter, not sightseer. I don't regard my Rex as the tool to keep going. It's always been a range anxiety mid reliever. Yesterday was a prime example. I did a lot of errands. Then it came up it was card night a day early at my buddies' house. Okay so that's going to put another 30 miles on the car that I wasn't planning on. I get in the car and I have 31 miles indicated. It's over 8 miles almost all uphill to get out to my buddies' house. If I didn't have that fine Rex in the back of the car, I would have been going on Ecopro+, having a cold rear end and not enjoying the fine torque electron stream I'm used to, and still worrying about it. Long story short, on he return journey, I got 1.5 miles away from my house and the Rex kicked in. And I didn't have to worry about it - at all, not even 1 percent. For me, it's worth the extra money. Yeah I'm sure it's not as quick as our Bev brothers, but the i3 is still plenty fast for stoplight Grand-Prix so I would 100% buy the Rex again, even though I rarely go more than 40 miles a day. It's just sometimes things come up and I need to keep driving. I don't want to end up on the side of the road like the 3 Leafs I've seen....

On that point, I'm sure the Leaf is a fine car and I was so hyped about it when it first came out, until I saw it up close. Total turn off for me. What's up with Nissan styling? Juke? Leaf? Cube? WTF? And VW consistantly rates at the bottom in Consumers Digest as most repairs last time I looked. I remember an Acura dealer told me they wouldn't even take a Toureg (and very new at the time) in on trade because they S--- so bad. That's what he said! I betcha the BMW is hands down a better car... it was a no brainer after the test drive...

For what it's worth. Don't mean to offend any Leaf or VW owners :roll:
 
For me, I just bought the REx 10/24 and glad I did. I had gone through all of the same iterations on the BEV. My commute is about 40 miles. I take my wife's car with the kids all the time now for any family trips. For the $4000 extra, I can rent a car or use the alternate feature through BMW many many times and still be way out front dollars wise. I couldn't come up with situations that weren't one off exceptions where I would need more miles and didn't have access to my wife's car. At the end, I went with the REx because the charging infrastructure is light in NJ. I was unsure of battery degradation over time and winter impact. I started projecting 20% reduction over winter and 20% reduction from degradation a few years out. I just didn't want to worry about it. In two weeks I've used the REx twice. The first time I went from work to see my son's lesson. I had the miles and should've just made it home on electric. I missed my exit, had to drive 3 miles up to the next one, then 3 miles down. That kicked me into range extender. The second time was purely by choice. I love driving the car and went shopping with the family after already having done my commute. It was nice to not have to worry. I'm still at a point in life where I would choose the 2 gallons of gas fill up in 10 minutes to sitting for 1/2 hour for a DC charger (that doesn't exist yet in NJ anyway). Make your own choice, but I'd leave you with this. I can't see you regretting the REx, you could regret not having it.

Best of luck in your choice.
 
Summing up and updating reasons to REx from a previous thread (http://www.mybmwi3.com/forum/posting.php?mode=edit&f=2&p=6778):

  • 1. It is incredibly inexpensive. You cannot find a liquid cooled, highly efficient, staggeringly low emission 34 hp gen-set anywhere for $3,850, much less one that imposes no volume penalty, and integrates seamlessly with the i3's electrical system.

    2. It imposes a negligible weight penalty, slowing the zero to sixty time by only 0.8 seconds (still quicker than any other EV except the Teslas), and increasing the fuel consumption to carry the additional weight by only 4.65% (seehttp://www.bmw.com/com/en/newvehicles/i/i3/2013/showroom/technical_data.html#m=i3_range_extender) or roughly $129 (assuming $0.11/kWh) over the course of 100,000 miles

    3. It eliminates the cost to rent or own and maintain a gasoline fueled vehicle for trips beyond a BEVs electric range.

    4. It eliminates both the embedded and produced pollution caused by renting or owning a gasoline fueled vehicle for trips beyond a BEVs electric range.

    5. It allows for a greater ratio of EV to gasoline powered driving for any given size battery bank:
    • - For EV only trips, it allows for full use of the battery's capacity, as the driver need not hold any EV range in reserve
      - For trips beyond the range of a BEV, it allows for not only EV use, but use of the the battery pack's full capacity. Consider a trip of 110 miles, only 100 of which could be reached by a BEV in its most economical mode. The BEV would stay in the garage, and the gasoline powered vehicle would travel the full 110 miles on gasoline only. A REx would be able to travel approximately 90 miles on electrical power, and need to travel only 20 miles using gasoline. 82% electric beats 0% electric.

    6. In many parts of the world, including much of the United States, well to wheel emissions per mile for an i3 REx operating on electricity are less than that of the lowest emission gasoline alternative, the Toyota Plug-In Prius (http://assets.climatecentral.org/pdfs/ClimateFriendlyCarsReport_Final.pdf). The greater amount of electric driving enabled by the REx (see point #5) makes it the more environmentally friendly choice than the combination of a BEV and an ICE vehicle in a great many places. The REx advantage is greater in areas of cleaner electrical generation (typically where a lower percentage of grid electricity comes from coal). If your solar array has excess capacity, the REx advantage is even greater.

    7. A BEV is limited to travel only between charging opportunities, making most trips outside of a roughly 30 mile radius inconvenient (3.5 hour wait to charge, although a 30 to 40 minute DC option is available to a tiny percentage of us), and many trips impossible (no realistic charging opportunity). A REx can travel pretty much from any point on a map to any other point on the map conveniently with only a few minute stop for fuel every hour or so.

    8. The REx offers the flexibility to change plans as situations change. An unexpected errand that would be impossible for a BEV to include in its planned range for the day would not even be a second thought for a REx

    9. Certified morons like myself occasionally forget to plug the car in at night. A REx would get me to work the next day with no issues, whereas doing the same with a BEV would cost me over $150 in cab fare.

And from another post on the same thread:

  • A decision to purchase a BEV would best be based on the minimum range requirement considering the worst case scenario, which would be the coldest temperature on the last day of either ownership or battery replacement. In my case the assumption that an initial range capacity of 75 miles at 60% highway speeds in fair temperatures will deteriorate to a level greater than the 58 mile range I need 10 years, and 100,000 miles down the road at 25 degrees F might logically drive me toward purchasing a BEV if I believed that temperature, mileage, and time erosion of that capacity to be less than 22%, but the 9 factors I listed made the decision to go with the REx an easy one.

RExInNJ eloquently summed it up - There are few things that better exemplify this old yarn than the REx: "Better to have it and not need it, than need it and not have it."
 
One small point to add to ultraturtle's excellent summary of REx benefits:

REx owners who have a PV solar installation in a place with highly variable weather like the UK have an extra option. Faced with a low battery on a dull day with sunnier weather forecast soon, they can postpone charging till the sun shines. If an urgent need arises in the meantime Rex will rescue them.

BEV owners in this situation would probably choose to charge immediately from the grid, at greater cost in money and carbon emissions.
 
I bought the Rex option too. I have had my i3 for 2 month's now and not used the Rex even once yet, but living in a rural area, 50 miles form a big city and in a state with very limited charging infrastructure, the Rex was the only way to go for me so I thought and still do.
 
There are certainly scenarios that make the REx a good buy, but depending on circumstances, for some, the BEV works just as well without the added outlay and maintenance. Now, at least in the USA, that maintenance cost is buried in the price and covered for the first 4-years, but it's still there.
 
Oh Ultraturtle, you make me boot up my laptop to address the inaccuracies in your above post!

Your views are "ultra-" tainted, I suspect, to justify your decision. Let me try and present a more balanced perspective.
(For background, I'm an automotive engineer, having worked for Toyota in Japan, GM and Ford in NA, and a small silicon valley auto startup. Note: I'm not a Tesla fan)

ultraturtle said:
Summing up and updating reasons to REx from a previous thread (http://www.mybmwi3.com/forum/posting.php?mode=edit&f=2&p=6778):

  • 1. It is incredibly inexpensive. You cannot find a liquid cooled, highly efficient, staggeringly low emission 34 hp gen-set anywhere for $3,850, much less one that imposes no volume penalty, and integrates seamlessly with the i3's electrical system.

    Actually, you can get a whole house generator for this price. It adds 10% to the price of the i3. It's not inexpensive at all. Especially given the limited range it adds (more on that below).

    2. It imposes a negligible weight penalty, slowing the zero to sixty time by only 0.8 seconds (still quicker than any other EV except the Teslas), and increasing the fuel consumption to carry the additional weight by only 4.65% (seehttp://www.bmw.com/com/en/newvehicles/i/i3/2013/showroom/technical_data.html#m=i3_range_extender) or roughly $129 (assuming $0.11/kWh) over the course of 100,000 miles

    0.8 seconds to 60 is HUGE. A Porsche 911 costs $15K more for 0.3 seconds improvement. You can definitely feel 0.3 seconds. A forum member has both the BEV and the REx, and he said there is a considerable difference in acceleration. You don't buy an i3 for acceleration, although a BMW should be sprightly; but just wanted to clear the air on this topic.
    The point is that the weight penalty is about 10%. That's a big deal, especially in a car where the engineers did the best they could to shave off as much weight as possible.

    The fuel consumption increase of 4.65% is optimistic. Factor in winter conditions when the heat pump in the BEV is much more efficient at heating the cabin and it's more like 7-10% (see my earlier posts).


    3. It eliminates the cost to rent or own and maintain a gasoline fueled vehicle for trips beyond a BEVs electric range.

    No way! Extremely wishful thinking. You're talking about ~60 miles of additional range (in North America). If your trip is longer than 80 + 60 miles, you still need another car… unless you want to deal with severe power loss at normal highway speeds or when climbing a grade with the REx running.

    4. It eliminates both the embedded and produced pollution caused by renting or owning a gasoline fueled vehicle for trips beyond a BEVs electric range.

    No. See #3.

    5. It allows for a greater ratio of EV to gasoline powered driving for any given size battery bank:
    • - For EV only trips, it allows for full use of the battery's capacity, as the driver need not hold any EV range in reserve

      No, again. Because the REx starts with 6-7% of battery level remaining. So you're not going to use that last 6-7%, unless you really like to live on the wild side and run the gas tank dry. But this is not healthy for a gas engine, and if you had this personality, you would be comfortable with the BEV :)

      - For trips beyond the range of a BEV, it allows for not only EV use, but use of the the battery pack's full capacity. Consider a trip of 110 miles, only 100 of which could be reached by a BEV in its most economical mode. The BEV would stay in the garage, and the gasoline powered vehicle would travel the full 110 miles on gasoline only. A REx would be able to travel approximately 90 miles on electrical power, and need to travel only 20 miles using gasoline. 82% electric beats 0% electric.

    Not quite right, because a true hybrid like a Prius is far more fuel efficient than running on REx.
    You are picking a REx-ideal range of 110 miles. Why? Why not the average length of an American road-trip, which is far more than 110 miles. A Prius is going to be about 50% more efficient than running on the REx.

    6. In many parts of the world, including much of the United States, well to wheel emissions per mile for an i3 REx operating on electricity are less than that of the lowest emission gasoline alternative, the Toyota Plug-In Prius (http://assets.climatecentral.org/pdfs/ClimateFriendlyCarsReport_Final.pdf). The greater amount of electric driving enabled by the REx (see point #5) makes it the more environmentally friendly choice than the combination of a BEV and an ICE vehicle in a great many places. The REx advantage is greater in areas of cleaner electrical generation (typically where a lower percentage of grid electricity comes from coal). If your solar array has excess capacity, the REx advantage is even greater.

    7. A BEV is limited to travel only between charging opportunities, making most trips outside of a roughly 30 mile radius inconvenient (3.5 hour wait to charge, although a 30 to 40 minute DC option is available to a tiny percentage of us), and many trips impossible (no realistic charging opportunity). A REx can travel pretty much from any point on a map to any other point on the map conveniently with only a few minute stop for fuel every hour or so.

    On the highway you'll be refueling the REx every 45 minutes. Hardly useful.

    8. The REx offers the flexibility to change plans as situations change. An unexpected errand that would be impossible for a BEV to include in its planned range for the day would not even be a second thought for a REx

    True - but the key word is "limited" flexibility. The REx adds very limited flexibility, at a big cost and weight penalty.

    9. Certified morons like myself occasionally forget to plug the car in at night. A REx would get me to work the next day with no issues, whereas doing the same with a BEV would cost me over $150 in cab fare.

Can't help you there. Do you forget to plug in your phone too? What do you do in those cases?!

And from another post on the same thread:

  • A decision to purchase a BEV would best be based on the minimum range requirement considering the worst case scenario, which would be the coldest temperature on the last day of either ownership or battery replacement. In my case the assumption that an initial range capacity of 75 miles at 60% highway speeds in fair temperatures will deteriorate to a level greater than the 58 mile range I need 10 years, and 100,000 miles down the road at 25 degrees F might logically drive me toward purchasing a BEV if I believed that temperature, mileage, and time erosion of that capacity to be less than 22%, but the 9 factors I listed made the decision to go with the REx an easy one.

No, no, no… This is wrong decision theory.
You don't buy a shoe based on the absolute worst case scenario. If you did, we would all have steel-toed, Goodyear-soled, knee-high patent leather boots.
It is not correct to base decisions on the absolute worst case. Why?
Because 99.9% of the time you are driving around in a compromise.

And for what it's worth, the REx is a HYBRID, in every sense of the word.
You are not "born electric" when you buy a REx. You have a car with a GASOLINE engine and fuel filler cap!

I'm not bashing the REx at all. I just want people to understand that it's a big compromise, and that if the BEV isn't for you, then the REx likely isn't either. It's a psychological placebo with limited benefit.

"
Click to expand...
 
Surge said:
I'm not bashing the REx at all. I just want people to understand that it's a big compromise, and that if the BEV isn't for you, then the REx likely isn't either. It's a psychological placebo with limited benefit.[/b]

"
Click to expand...
[/quote]
Surge, perhaps I could also add some perspective, given that your signature seems to have been 'soon to be ordered' since I joined the forum early this year, the transition from undecided to neither REx nor BEV to a definitive 'not' does seem quite sudden (but doesn't need explanation)!

If my REx is a placebo for a car that is unsuited to my needs then I'll carry on taking the placebo because it enables me happily to plan long journeys where the distance between just two of the successive CCS chargers on the route exceeds electric range by just a few miles or when there is a possibility that a CCS charger is u/s. Without the REx these journeys wouldn't be viable and I'd be driving an ICE, with the REx I can painlessly make such journeys. No detailed technical analysis required!
 
I have to agree with RJSATLBA. Of course the REx is a compromise but ALL cars are a compromise. We too live in a area where some of our trips are into areas where any chargers let alone rapid chargers are a rarity. In such cases we would have to take an ICE clocking up far more fossil miles than than the Rex has been needed for in our 6 months of use. Overall it becomes purer than a BEV + ICE. I would love to be able to use a pure BEV alone but at the present state of the art this is not possible. The i3 REx is the best compromise for us and for many others too.
 

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