Range Question

[Surge]

The BEV would gain another 4-5% range compared to the REx due to the reduced weight.

I think the BEV can do about 20% better range than the REx, here's why:
- weight is 10% lighter, so 10% better range
- in the US/Canada, you cannot use 6% of the battery in the REx, since the gas gen turns on automatically at this SOC, so +6% for the BEV
- heat pump - depending on outside temp and how much you use the heater, the BEV heat pump is 30% more efficient (vs. the regular heater, I imagine); BMWi3Owner.com in "BMW i3 in Nordic Winter" posted that the heat pump adds about 5-10 km (~6 miles) to the range, or another 7%

Adding it up, you get 23% improvement in range with the BEV vs. REx (on battery alone, of course)

Also, where have you seen the heated steering wheel option for the i3? I would love to get it, but have not seen it offered in US/Canada. I'm sure it can be added after you take delivery, by the dealer.

 

[MikeS]

The BEV would gain another 4-5% range compared to the REx due to the reduced weight.
True,but only if the driver and passenger weights were the same! :evil:

 

[bxb40]

The 75 miles would be an estimate on the very high side. If you drive somewhere and you stop 1 hour, the batteries will be cold when you return to the car. If you have 1-2 passengers, another hit on the mileage. I'd say for 2 passengers in winter, leaving home all charged and with a warm battery, you can get probably do a 60 miles round trip once you stop for 1+ hour in -15C or lower temperatures. Of course, this is assuming the destination is not a covered garage with a charger BTW, you'll need to heat the cabin because the rear seats are not heated...
Also, winter tires will also eat into your range because they have higher grip, so friction - but safety first, so at -15C are probably a must (all-season tires get too stiff at those temps and their grip, even in the dry, is not optimal).

 

[bxb40]

- weight is 10% lighter, so 10% better range
- in the US/Canada, you cannot use 6% of the battery in the REx, since the gas gen turns on automatically at this SOC, so +6% for the BEV

How was the 10% calculation done? At least at higher speeds, the weight is less important compared to the air friction, which is the same in both cars. So for mix driving, make it 5% (assuming the original calculation you referred to is correct).

Why do you say you cannot use 6% of SOC in the US REX? Did you read anywhere that after the gasoline is depleted, the car will just stop while having 6% still available? I don't think so, you'll use those 6% to get to the nearest gas station... It may be a limited limp-like mode, but if that is the case, the BEV will have the same issue (and I did not see any report on such, so it most likely not the case).

 

[Surge]

The 75 miles would be an estimate on the very high side. If you drive somewhere and you stop 1 hour, the batteries will be cold when you return to the car. If you have 1-2 passengers, another hit on the mileage. I'd say for 2 passengers in winter, leaving home all charged and with a warm battery, you can get probably do a 60 miles round trip once you stop for 1+ hour in -15C or lower temperatures. Of course, this is assuming the destination is not a covered garage with a charger BTW, you'll need to heat the cabin because the rear seats are not heated...
Also, winter tires will also eat into your range because they have higher grip, so friction - but safety first, so at -15C are probably a must (all-season tires get too stiff at those temps and their grip, even in the dry, is not optimal).

Thanks, that's also what I was thinking. 60 miles for the BEV. And about 10-15% less for the REx (depending how much you use the heater)
That's 5% due to extra weight/higher Cd (not 10%), the 5% was confirmed by others in another thread
Then another 5-10% for the heat pump in the BEV
So you're looking at about 50 miles range with the REx, before the gas engine comes on.

 

[Surge]

Why do you say you cannot use 6% of SOC in the US REX? Did you read anywhere that after the gasoline is depleted, the car will just stop while having 6% still available? I don't think so, you'll use those 6% to get to the nearest gas station... It may be a limited limp-like mode, but if that is the case, the BEV will have the same issue (and I did not see any report on such, so it most likely not the case).

You bring up a good point, and it got me thinking. I don't think anyone knows whether or not the last 6% of the battery will be useable with the US/Canada REx.
What happens when the fuel runs out? First- it's not at all good practice to run a gas engine until the fuel runs dry. Any sediment, and moisture will get into the fuel injectors. So you probably won't want to use the full range of the REx.

But leaving that aside, what happens when the fuel runs out? Will the i3 keep trying to start the gas engine? Or will it be smart enough to know the fuel tank is empty and let you continue using the battery? Not sure, because in the US/Canada, BMW has implemented this stupid automatic REx engagement whenever the battery is at 6% or below.

If the car is continuously trying to restart the engine, that's not going to be good for range, I imagine.

So I would put a question mark beside whether or not you can use the last 6%.

 

[BoMW]

Why do you say you cannot use 6% of SOC in the US REX? Did you read anywhere that after the gasoline is depleted, the car will just stop while having 6% still available? I

So I would put a question mark beside whether or not you can use the last 6%.

I have used the last 6%. I have ran the battery down to when the Rex licks in, normally leaving me with 5 miles. I have seen this deplete to zero even though Rex has been activated. At very low speed I.e. when parking the Rex has switched off and the battery has taken over.

 

[mindmachine]

Why do you say you cannot use 6% of SOC in the US REX? Did you read anywhere that after the gasoline is depleted, the car will just stop while having 6% still available? I don't think so, you'll use those 6% to get to the nearest gas station... It may be a limited limp-like mode, but if that is the case, the BEV will have the same issue (and I did not see any report on such, so it most likely not the case).

You bring up a good point, and it got me thinking. I don't think anyone knows whether or not the last 6% of the battery will be useable with the US/Canada REx.
What happens when the fuel runs out? First- it's not at all good practice to run a gas engine until the fuel runs dry. Any sediment, and moisture will get into the fuel injectors. So you probably won't want to use the full range of the REx.

But leaving that aside, what happens when the fuel runs out? Will the i3 keep trying to start the gas engine? Or will it be smart enough to know the fuel tank is empty and let you continue using the battery? Not sure, because in the US/Canada, BMW has implemented this stupid automatic REx engagement whenever the battery is at 6% or below.

If the car is continuously trying to restart the engine, that's not going to be good for range, I imagine.

So I would put a question mark beside whether or not you can use the last 6%.

This was discussed in another thread by owners in the UK. The Rex shuts itself off before it runs totally dry. Additionally all i3 Rex equipped vehicles have a set point to turn the Rex on. Originally it was 20% SOC, but recent reports suggest that BMW may have adjusted later production to the 6.5% SOC. Finally, after the Rex runs low on fuel and stops, the battery is available and can be run down further to a lower SOC same as in the BEV.

 

[Surge]

Why do you say you cannot use 6% of SOC in the US REX? Did you read anywhere that after the gasoline is depleted, the car will just stop while having 6% still available? I

So I would put a question mark beside whether or not you can use the last 6%.

I have used the last 6%. I have ran the battery down to when the Rex licks in, normally leaving me with 5 miles. I have seen this deplete to zero even though Rex has been activated. At very low speed I.e. when parking the Rex has switched off and the battery has taken over.

Right but I gather you are in Europe. The REx will behave differently in the US/Canada - it will not be manually operable - will only turn on when batt is <6.5%, apparently.

 

[Surge]

This was discussed in another thread by owners in the UK. The Rex shuts itself off before it runs totally dry. Additionally all i3 Rex equipped vehicles have a set point to turn the Rex on. Originally it was 20% SOC, but recent reports suggest that BMW may have adjusted later production to the 6.5% SOC. Finally, after the Rex runs low on fuel and stops, the battery is available and can be run down further to a lower SOC same as in the BEV.

Ok, perfect then!