Is it really a ‘city car’?

[MikeS]

I ask as I have had my i3 for more than a year now so had a chance to drive it from a late summer through a uk winter and back to summer again so have seen the effect of temp on range. However, more important seems to be the effect of the length of journey. Typically, if I use my car from lots of short journeys (air con/heating always off) then at the moment I get around 77miles with similar weather if i take the car for a longish trip 40+ miles there an back I get 90+ miles. No preconditioning and a rest of around 1hr 30min between the 2 longer journeys. So in my case the i3 performs significantly better if used for longer trips.

 

[WoodlandHills]

Lots of people overlook the Mega part of Mega-City. BMW designed this not as a pure dense urban runabout, but as vehicle for urban areas like greater London, Los Angeles, Paris, etc. Where many if not most buyers will spend significant time on motorways and freeways getting between their homes and their work/play and travel longer distances. A pure city car with a 60+ mile range would have no need of a REx and yet BMW designed one into their BEV. That's a clear indication that BMW had plans for more than a downtown city car.

 

[stumbledotcom]

The city car label applies to more than range. It's all the design choices: overall size, minimal overhangs front and rear, offering pedestrian sensing and collision mitigation instead of blind spot detection, even the door configuration. Every vehicle regardless of fuel type is more efficient when driven continuously without frequent start and stops. An EV is no different. My gas-powered 3 series has a range of about 120 miles when driven exclusively in the city and 330+ on the highway.

It's been documented elsewhere that BMW added the REX option relatively late in the i3 development cycle. It exists more for marketing purposes than as a feature expected to be used day in/day out.

 

[MikeS]

My focus for the question is on the range changes depending on long or short journeys. Ive no problem with the car, just wondering why it performs so much better on longer journeys.

 

[alohart]

Typically, if I use my car from lots of short journeys (air con/heating always off) then at the moment I get around 77miles with similar weather if i take the car for a longish trip 40+ miles there an back I get 90+ miles. No preconditioning and a rest of around 1hr 30min between the 2 longer journeys. So in my case the i3 performs significantly better if used for longer trips.

Are the 77 and 90+ miles the range estimates or actual distances that could have been driven assuming an 18.8 kWh usable battery capacity and your average efficiency in mi/kWh on these particular trips? If they are range estimates, then the estimates are way off, likely due to the poor algorithms that the "guestimator" uses. Apparently these algorithms have been improved in the March, 2015, software update.

The i3 is typically much more efficient at slow speeds, even in stop-and-go urban traffic, than at fast highway speeds. If your longer trips weren't at fast highway speeds, then your range could be better than your shorter trips if these shorter trips included lots of stop-and-go with spirited accelerations and aggressive braking.

 

[MikeS]

The ranges quoted are actual ranges. I typically get about 4.5m/kwh and my overall average is 4.2. There is very rarely any spirited accelerations and the short trips are generally without any significant stops. The longer trip was a variety of roads driven in comfort mode and speeds between 75 and 30 mph. The longer trip also included some spirited acceleration as I was showing (off) the car to an EV sceptical friend.

 

[i3an]

On longer continuous trips the battery reaches and maintains its optimum temperature and achieves maximum range; on shorter trips the battery may never reach optimum temperature, and cools off anyway when parked, thus reducing overall range.

 

[MikeS]

On longer continuous trips the battery reaches and maintains its optimum temperature and achieves maximum range; on shorter trips the battery may never reach optimum temperature, and cools off anyway when parked, thus reducing overall range.

Yes, thats what I put it down to. Hence my question about it really being a city car.

 

[jadnashuanh]

Any vehicle will get better range when driven at a constant speed, doesn't matter if it is an ICE or an EV. The energy conversion from liquid fuel to motion isn't great...with an EV, it approaches 100%. In the winter, one big difference is how you heat the cabin, here, an ICE has an advantage, but those don't run as efficiently on short runs, only once fully warmed up and that can take a number of miles when it is frigid outside...an EV, especially if you can precondition it while on the EVSE, can be about as efficient on the first mile...way different than an ICE.

Regen, ideally would never be used because you are going at a constant speed. It never recovers anywhere near the full amount it took to get up to speed, so if you can maintain, you'll get better range. But, if you're going to be running around town, stop and go, an EV will be more efficient than an ICE, and comparing those two situations is where an EV shines. The available storage of energy in an EV is problematic...increase the battery size, increase the weight and therefore decrease the range. A fully optioned Tesla has nearly 4x the battery capacity, but doesn't get anywhere near 4x the range of an i3. At some point, adding more batteries would start to significantly decrease maximum range because of the weight, and the volume becomes an issue as well. I think the i3 hit a good sweet spot for what it was designed for.

 

[MikeS]

None of my journeys are at anywhere near constant speeds owing to the highly congested roads in England and I never use the heating and very rarely use the air con. The original comparison between 77 to 90+ mile range was with no heating or air con, in very similar temperatures. So it really does seem to bedgown to the cost of maintaining the battery temp. Therefore if it was designed as a city car then BMW did not get it right as its better on longer journeys.

To be clear, I like the i3 a lot and have few complaints. I just find the range difference irksome.

 

[noakey]

None of my journeys are at anywhere near constant speeds owing to the highly congested roads in England and I never use the heating and very rarely use the air con. The original comparison between 77 to 90+ mile range was with no heating or air con, in very similar temperatures. So it really does seem to bedgown to the cost of maintaining the battery temp. Therefore if it was designed as a city car then BMW did not get it right as its better on longer journeys.

To be clear, I like the i3 a lot and have few complaints. I just find the range difference irksome.

Hi

Hi MikeS..

I agree with your conclusion re: the battery temp... I have similar experiences.. I can cruise for 90 miles at 60mph on a single run, but pop to town (7 miles) do some shopping, drive home, pop to supermarket (5 miles), drive home the charge is almost half used, suggesting a range of around 50-60 miles...

 

[MikeS]

Noakey - Exactly.

I was getting a tad disappointed with the range until I took a longer trip…..