[tpanda]

Hi all,

I bought a 2015 BMW i8 about six weeks ago, Protonic Blue exterior with Giga Amido Black interior, just over 30,000 miles. I absolutely love the car, how it looks, how it drives, and that it has just enough of a back seat to fit children. I bought it with the plan to commute daily without using any gas. I work about 6 miles from home, and while I can easily make the one-way trip, and I can plug it in both at home and at work, I had been hoping the car would easily do the round trip entirely on electricity, for those days when the chargers at work are all in use. Instead, it’s right on the edge of the range: when fully charged, the car displays an electric range of 12–13 miles, and that tends to be accurate to where it will force the gas engine on.

For example, this morning: I started with the car plugged in overnight at home, and drove to work, with Max eDrive enabled and in ECO PRO mode. With a fairly light foot on the throttle, the battery went from 100.0% to 50.0% in 24 minutes, 6.4 miles of city driving with moderate traffic, with one stop to drop off the kid at school.

The trip computer (which I reset at the beginning) shows my consumption was 2.5 mi/kWh (or 24.8 kWh/100km). This works out to a total use of 2.56 kWh for 50.0% of battery capacity, for a full capacity of 5.12 kWh. I’ve read the battery is supposed to have 5.2 kWh of useful capacity, so if this is accurate, it’s encouraging. But I don’t know how accurate it is; fuel economy displays on gas cars I’ve owned have been off up to 20% from what I put in at the tank.

Over the last month of driving, 2.5 mi/kWh seems typical for the drive; sometimes I’ve gotten it as high as 3.0 mi/kWh if I’m extremely gentle on throttle and brake and don’t hit too many red lights, but this isn’t something I can get the car to reproduce every day, it feels like there are other factors (weather?). And when I can get the trip computer closer to 3 mi/kWh, I can get an extra few electric miles out of the car.

But…

The EPA ratings for a 2015 i8 on fueleconomy.org show that the vehicle is rated for “0–14 miles” of all-electric range. That’s not too far off from the 12–13 miles I get now, but it also says “43 kWh/100mi”. That works out to 2.32 mi/kWh, and I’m getting 2.5 or better, so if the EPA figures are correct I should be getting 15 miles, or 18 on the days when I can push it to 3.0 mi/kWh. I’m not. And the EPA figures also work out to (43 * 14/100) 6.02 kWh of usable capacity. So either the EPA figures are wrong (especially since I’ve read 5.2 kWh is the figure) or my battery has 15% less capacity than it should.

I also notice that when I plug it into a charger, it thinks its delivering more energy than I expect. For example, this morning I plugged it in, and to charge from 50.0% back up to 100.0%, the charger (a ChargePoint commercial unit) reports it delivered 3.28 kWh. If the trip computer is accurate that I had depleted 2.56 kWh of capacity, that would mean the charging efficiency is 78%, which seem a little low.

I am concerned because I’ve had range trouble with the car since I bought it: when I got it, the car displayed and delivered 8–10 miles of all-electric range. I took it to the local BMW dealer, who diagnosed a fault in the “low voltage battery” that was causing excess power drain and replaced it (I’m pretty sure they just replaced the 12V battery, which for some reason they had to ship across the country and it took two weeks to complete.) They said everything else was fine, and after that the range increased to the 12–13 miles I’m seeing now. But I’m nervous that something else might be wrong.

Looking through the forum and Internet reports, I’ve seen occasional reports of 20–25 miles of electric range in an i8, which seems like it would be completely impossible with the vehicle I have, no matter how or where I drive it. Is my 12–13 miles of all-electric range typical of what others see, or should I be taking it back to the dealer and having them look for something else?

Thanks!

[NGR]

I think most owners will agree to getting similar e-range.
Mine rarely goes above 15/6 miles and in these colder temps is usually showing 13 on a full charge, sometimes as low as 11.

It will be warmer in CA but AC uses juice etc...

I get the better predicted range when I've been on a longer journey and have combined ICE with battery. Running purely on electric for short journeys always results in a lower predicted range - possibly something to do with the hilly terrain around here?

[Maxxsirrah]

had my car from new, best i've had is 16 miles and it's much worse in winter. temperature has a big impact. 12 to 13 miles in winter is typical for me.

[evanevery]

The i8 is a tech toy at best. If you're concerned about electric range you bought the wrong EV...

[DeadWeight]

Probably goes without saying since the OP seems pretty well versed in the technical details, but batteries deteriorate slightly with each charge cycle until they eventually need to be replaced.

I'm not surprised to see marginally below spec performance from a 4 year old battery pack. The numbers are actually a little better than I would've expected.

[MichaelJohn]

I also live in the Bay Area so I am operating in similar temperatures. Range is definitely down in colder weather - it’s the same with my Zero motorcycle. However, my range has exceeded my expectations with the i8. In warmer weather I get high teens/low twenties with a high of 24. Now i’m getting 15-18 miles per charge. I do have to drive VERY gently in Eco Pro to achieve the higher numbers but it’s kind of fun sometimes. The predicted range is all about the last drive and doesn’t mean much unless you can replicate your last trip. I have seen predicted ranges in the low 20’s and gotten 15 miles because I drove differently. I have seen the reverse as well. My car is a ‘15 with 9,000 miles so maybe my battery is less depleted.

I disagree that being concerned with range means we bought the wrong EV. That doesn’t make sense. Why shouldn’t we be concerned with range? I wouldn’t have bought the car if it only had 10 miles of EV range but 18-20 means that I can get all of my local errands done on electric only if I so choose. Just because the i8’s electric range is limited doesn’t mean it can’t be used as a viable EV. I have done it scores of times.

[Ionicsilveri8]

When I picked up my second hand i8 (2016 model) it was fully charged but only showed a predicted range of 8 miles. The salesman wasn’t that clued up but I have since learnt that (as MichaelJohn says above) this figure depends on how the car was driven on the last trip it took which in my case was pootling around a garage forecourt between the workshop, the valeting bay and the sales garage. With careful driving I have seen this predicted range go up to 26 miles but that is only predicted however!

The best advice I was ever given was to use the pre-conditiong function. If you know when you are going out in the morning then leave the car on charge and set the departure time in the car. That way, the car warms the battery to its optimal temperature (by using the power from the house) and for us in the UK, it also warms the cabin in preparation for the trip. Warming the cabin and the battery pack is all done without using the charge in the battery because you are still plugged in. If you don’t do this then when you set off, an element of your charge will be used both in warming the battery pack and the cabin which of course reduces your range.

Sort of makes sense, apologies if you knew this but I didn’t see it mentioned in the trail. I regularly have a range indicated of the low 20s. Don’t forget also that in the UK at least, the batteries have a warranty of 8 years so if they are failing, it may be worth taking it in?

[Aye-eight]

OP’s numbers suggest that it’s not the battery capacity that’s the issue here. The numbers seem fairly normal. And their accuracy typically gets better with more distance driven (e.g. battery to empty instead of 50% charge).

The 2.5 mi/kWh or 24.8 kWh/100km is where it’s at. I’ve driven my i8 up to 40km (25 mi) on a single charge. This can work in the summer if you’re cruising empty streets in a straight line with no stoplights. Rare, but it happens. When it does, my electrical consumption is in the range of 13-14 kWh/100 km or roughly 5 mi/kWh.

“Light foot” is subjective - esp. if you’re sitting in a sporty looking car. You have to make a real effort to max out the range. Plus, in the winter, you’re also likely to use more headlights, wipers, heater, battery conditioner ... all of which will reduce range.

And your range indication for full charge is dependent on your last drive(s). Drivng extremely conservatively for a day or two in a row will drive up the range number on your next charge.

[Aye-eight]

Originally Posted by Ionicsilveri8

...

The best advice I was ever given was to use the pre-conditiong function. If you know when you are going out in the morning then leave the car on charge and set the departure time in the car. That way, the car warms the battery to its optimal temperature (by using the power from the house) and for us in the UK, it also warms the cabin in preparation for the trip. Warming the cabin and the battery pack is all done without using the charge in the battery because you are still plugged in. If you don’t do this then when you set off, an element of your charge will be used both in warming the battery pack and the cabin which of course reduces your range.

...

Good advice. With one caveat: if you use precondition and your trips starts after the off-peak tariff ends, don’t set the car to “off peak charging”. Because then it will pre-condition the car from the battery and not use shore power. Or, just set the off-peak times accordingly, I suppose.

[stressdoc]

Hence the utility of the added range of the 2019 model...

[tpanda]

Thanks everyone for their replies. I tried out preconditioning the car before driving this morning, and it made a significant difference. I drove approximately the same route as I did last week, 6.2 miles in 24 minutes, and instead of 2.5 mi/kWh and 50.0% of battery used, I did a solid 3.0 mi/kWh using only 35% of the battery. It’s interesting that in addition to 20% better efficiency, the usable battery capacity itself seemed to go up by 15% (the math works out to 5.9 kWh instead of 5.12 kWh total battery capacity).

So unless there’s a measurement error, that works out to an electric range increase from 13 miles to almost 18 miles! So temperature definitely makes a difference; thanks for the tips and that’s definitely something I’ll keep in mind.

I definitely agree that a BMW i8 is a tech toy, but that doesn’t mean I don’t expect it to work correctly. To me, a “tech toy” is a product that incorporates cutting-edge technological innovations, and that means that you’re paying extra money for questionable value. For example, you can spend $600 on a “smart” toaster oven that’s Wi-Fi connected, streams video of your food cooking, and automatically recognizes food you put in and determines how to cook it. If I bought one of these (I haven’t yet), I’d be prepared to find out that these features are useless and not worth $600 to me, and to learn that the automatic cooking tell the difference between an egg and a potato, but if the Wi-Fi video streaming didn’t work I’d be upset, and if it didn’t at least cook as well as a $30 toaster oven I can buy at Target I’d be returning it. But when the BMW i8 was introduced, the plug-in hybrid was not a new concept. The Chevy Volt had been shipping for about four years by the time the first production i8 was delivered in 2014, and so I don't consider the mere fact of the EV mode to be a "toy" feature. The $137,500 MSRP of a base 2015 i8 was four times that of a base 2015 Volt ($34,345 with an all-electric range of 38 miles), but the extra money isn't for the concept of a plug-in car, it's for performance, handling, appearance, materials, etc. And I still paid twice as much for a used i8 as a brand-new Chevy (the 2019 Volt has a 53 mile range), for those same reasons.

But my concern wasn’t with whether the BMW i8 was a reasonable short-range electric vehicle. I saw plenty of reviews and descriptions before buying the car that suggested it should work fine (I even rented one and drove it to work and back to purchase to confirm, thanks Turo!) My concern was that my particular vehicle had already had one failure that caused diminished range, and I wanted to compare notes to find out whether I should be pursuing additional fixes before the warranty expires. But it seems like my car is working like like it should, and so I’ll stop being anxious and instead just enjoy my time with the vehicle!

[z4driver]

on a slight side not does anyone know what the upside down triangle above the battery charge means?

[drlonline]

Originally Posted by z4driver

on a slight side not does anyone know what the upside down triangle above the battery charge means?

Here is the explanation from the owners manual.

[Ionicsilveri8]

Originally Posted by tpanda

I tried out preconditioning the car before driving this morning, and it made a significant difference.

You’re welcome!

[Epirali]

Late to party but if you turn off the AC/heat, fully charge and precondition and drive carefully you may get 18-19 miles out of the car in around 50F. Warmer will give you more and colder will drop it rapidly.

[Ionicsilveri8]

Econ pro is a given for best range also...