IX range - promising for the i4
-
BMW i4 Reservation Tracker: Add Yours Here!
1 - 18 of 18 Posts
Joined
·
384 Posts
Since the configurator has shown more like 500km, and BMW tends to mean it when they write the specs of their cars, I would be disappointed if it can only go 400km. I didn’t watch the whole review there, but if they’re doing plenty of stop and go in addition to autobahn speeds, it’s not so bad.
It’s really crazy how the iX is just a good hundred kg heavier than the i4. The use of aluminum space frame and carbon fiber along with the battery really did wonders for weight save. So I’m thinking better aero but motors tuned less for efficiency should leave it slightly better off than the iX.
It’s really crazy how the iX is just a good hundred kg heavier than the i4. The use of aluminum space frame and carbon fiber along with the battery really did wonders for weight save. So I’m thinking better aero but motors tuned less for efficiency should leave it slightly better off than the iX.
Yes, I think so. The big difference is the size of the battery - 105 kwh in the iX compared to 80 in the i4
Joined
·
286 Posts
According to my highly scientific calculations
iX
drag coefficient 0.25
width 1.97m
height 1.70m
i4
drag coefficien: 0.24
width 1.85m
height 1.45m
drag force iX / i4 => 0.25 * 1,97 * 1.70 / (0.24 * 1.85 * 1.45) = 1.30
Hence with speed and distance traveled equal the iX should have 30% more work to do to overcome air drag.
However when adjusting for battery
iX = 105 vs i4 = 80.7 => 1.30 * 80.7 / 105 = 1.00
This would be about the same range!
Of course there is still weight, engine efficiency, friction, tire rotation, etc which will have significant influence.
iX
drag coefficient 0.25
width 1.97m
height 1.70m
i4
drag coefficien: 0.24
width 1.85m
height 1.45m
drag force iX / i4 => 0.25 * 1,97 * 1.70 / (0.24 * 1.85 * 1.45) = 1.30
Hence with speed and distance traveled equal the iX should have 30% more work to do to overcome air drag.
However when adjusting for battery
iX = 105 vs i4 = 80.7 => 1.30 * 80.7 / 105 = 1.00
This would be about the same range!
Of course there is still weight, engine efficiency, friction, tire rotation, etc which will have significant influence.
Yes it’s true, but calculations above are for drag force not drag coefficient
Joined
·
286 Posts
Drag equation (Wikipedia)Yes it’s true, but calculations above are for drag force not drag coefficient
Everything else equal it differs between iX and i4 in drag coefficient and reference area (approximately frontal area).
Work is force times displacement (distance traveled).
Joined
·
1,078 Posts
Bjorn, carwow, Thomas and other reviewers will sed light to the actual i4 consumption and range with extreme details. (Especially Bjorn Nyland who is famous for testing every aspect of charging).
We just have to wait until Oct. 13.
(If I was a gambling man I would say let's put some bets about the exact measured or projected range. One number each member, to see who will get closer.) 😈
We just have to wait until Oct. 13.
(If I was a gambling man I would say let's put some bets about the exact measured or projected range. One number each member, to see who will get closer.) 😈
Joined
·
1,078 Posts
Let's add the BMW iX3 to the equation!
I remind you that it has:
According to the title of this extensive (>30 min) real-life test video the range/consumption are:
BMW iX3 range: real-life test: 462 km (287 mi) with 4.17 mpkWh, 14.9 kWh/100 km
P.S. For my friend Inside...There is a lot of "Assisted View" in the video (after 4:07) and ..<sigh>.. I don't think that is useful much...It misses cars..It is representing Vans as regular sedans and doesn't show ...turns neither the opposite stream of cars.
So it's not some fancy 3D all around view of what is happening near the car.
It's so gimmicky that I might skip, after all, the professional and option the Plus and save 1K of €.
I remind you that it has:
| Battery Capacity | 80.0 kWh |
| Battery Useable | 74.0 kWh |
According to the title of this extensive (>30 min) real-life test video the range/consumption are:
BMW iX3 range: real-life test: 462 km (287 mi) with 4.17 mpkWh, 14.9 kWh/100 km
P.S. For my friend Inside...There is a lot of "Assisted View" in the video (after 4:07) and ..<sigh>.. I don't think that is useful much...It misses cars..It is representing Vans as regular sedans and doesn't show ...turns neither the opposite stream of cars.
So it's not some fancy 3D all around view of what is happening near the car.
It's so gimmicky that I might skip, after all, the professional and option the Plus and save 1K of €.
Joined
·
1,078 Posts
Are you referring to the Assisted view?
Hm. It will be interesting to see how it progressed to the iDrive 8. If it is about the same than the technology is hopeless.
Joined
·
769 Posts
Thanks for the video. Hopefully it will have progressed on iDrive8. But at the moment, I will not be choosing the professional assisted view package. I may only be using the self driving capabilities a couple of times a year, so it really isent worth it. the autopilot with stop and go will be what I use on longer trips at the highway.
Joined
·
286 Posts
Joined
·
1,078 Posts
I was positive that I would included it, to showing it to friends and spare me from comments like "You know Tesla has this radar that..." but now I think that I leave it out (only get Plus, not Pro).
To be useful had to be way more advanced.
Show the rear in greater distance. Maybe working in conjunction with the navigation and showing lanes and turns.
Like an aerial view of what is happening around the car.
That could be useful.
To be useful had to be way more advanced.
Show the rear in greater distance. Maybe working in conjunction with the navigation and showing lanes and turns.
Like an aerial view of what is happening around the car.
That could be useful.
Joined
·
352 Posts
Yes, the assisted view. At times it doesn't recognize two lane on either side.
On the Norwegian configurator it seems to be included in some pack, so we can't deselect it, not that I mind, I like gimmicky things.
But I highly doubt it being improved much in the comming updates, but we will see I guess.
i4 e40 msport 19" 859M Sunset Orange, cognac vernasca, open pore oak trim
Joined
·
2,480 Posts
Thinking about drag, BMW has published not only the drag coefficient but the refernce area, so we can compute the drag force vs speed. (1/2 ρ V2 CDA) Power is the force times the speed.
Rolling resistance in the wheels is an almost constant force until high speeds, and is in the order of 1.4% of the weight.
Power train losses are some percentage of the power used. So if the drive train is 80% efficient the energy drain on the battery is power needed to drive the car, divided by the efficiency.
Putting these factors together, the power used at a given travel speed is:
P = (k1*V + k2*V3)
Where k1 is the rolling resistance divided by the efficiency, and k2 is 1/2 ρ CDA divided by the efficiency.
So I set up a calculation with the speeds and durations of the EPA test cycle to get the total energy drain for the cycle, then the range of the battery. I also put in a usage of 2 kW for the cooling and heating cycle of the test. Then I adjusted the parameters to get the estimated EPA range of 300 miles.
This gave me an efficiency of 85%, which is about what Tesla says for their cars, and a rolling resistence of 1.4%. With those numbers I can estimate the power used for each travel speed.
If you have a vehicle you can record the power usage for several fixed speeds and solve for the k values for your particular vehicle.
One burning question is the delay due to recharging. You can figure that out by knowing the rate of power usage at your intended speed during a trip, and the charging rate of the fast charges you will use along the way. Both values are given in kW and from the above you can the power for driving, call it R1.
The charging rate, R2, is the speed of your charger. The fraction of your travel time spent driving is
R2 / (R1 + R2)
Your effective travel speed is your actual speed times this fraction of time driving.
The graph below plots this effective speed for several driving speeds.
1 - 18 of 18 Posts
