i3 Noob Questions (brake and AC performance?)

Hi all!
I'm new here! I just picked up a new-to-me 2017 i3 REx this week. I have owned a LEAF since 2012 and a Model 3 since 2018, so I'm not new to EV's, just an i3 noob. I have a few i3 questions that hopefully some of you expirenced i3 owners might be able to help with.

The brake pedal force required to activate ABS (emergency braking) is at least twice that of any other vehicle I have ever driven and requires that the pedal be pushed to the floor. Is this normal? This car seems to have sat for about 9 months before I purchased it. The rotors are pitted from corrosion.

It has been 90F+ and humid here the last few days. In order to keep the cabin at about 68F-70F it is required to keep the climate control set to 62F. Is this normal behavior? (the car is set to comfort mode and the ac system is set to auto.)

Thanks for any help!
-Sean

Having owned our 2014 i3 since it was new, I don't normally use friction brakes for decelerating or stopping (one-pedal urban/suburban driving almost always under the control of ACC) and don't recall ever braking so hard that traction was lost and ABS activated. If traction isn't lost, ABS shouldn't be activated, so maybe your i3 wasn't losing traction during hard braking. Nevertheless, I'm surprised that your brake pedal can be pressed to the floor. That doesn't seem normal.

Even though our i3 hasn't been parked for 9 months, its brake rotors are always rusty because they aren't used very often in our humid, salty environment.

The maximum ambient temperature here these days is ~90º F. Our i3 cabin is comfortable with the A/C set to AUTO and the thermostat set to 74º F. However, we're comfortable with our apartment thermostat set to 77º F, so a thermostat setting in our i3 below 74º F would be uncomfortably cold for us. Nevertheless, it doesn't seem normal to have to set the A/C thermostat to 62º F to maintain a cabin temperature of 68º - 70º F.

Hello sandi –

Congratulations on your new ride and welcome to the forum!

Most of my driving experience is with BMWs and the amount of pressure / pedal travel to reach ABS engagement on my 2014 i3 feels about the same as the other BMWs I've owned.

A properly-serviced i3 should have a brake fluid change every two years. If the prior owner neglected service, lived in a humid environment, and opened the brake fluid reservoir then perhaps the brake fluid could have absorbed some moisture (leading to a soft pedal) but otherwise what you describe is not normal.

If the pedal truly "goes to the floor" then there may be a brake fluid leak or failed master cylinder. In five years on this board I've not heard of either of those happening in an i3.

Regarding A/C, I've found the one fitted to the i3 to be very capable in exterior temps above 110°F (dry). Needing to set Auto 62°F with exterior temps around 90°F doesn't sound right. Note that I have all windows tinted, including front and rear, which I think is a requirement for this car in a hot environment.

Was your purchase a CPO from a BMW dealer? If so, I'd have some questions for the service department.

One thing that may be counterintuitive is the fan...on the i3, it's sort of an aggressiveness adjustment, so first thing, move it up a couple of notches.

I'm in Austin, with a new-to-me for 1 1/2 months 2018. I set the AC at 74 degrees and find that the AC is great in comfort mode at 108 degrees and acceptable in Eco Pro at up to maybe 105. I do try to get my driving in before noon. That's as hot as I have experienced so far this summer. We have at least another week of over 100 every day.

I'm more concerned with the resisitive heat (Rex) next winter impacting the mileage. Wish I had the heat pump.

alohart said:

Having owned our 2014 i3 since it was new, I don't normally use friction brakes for decelerating or stopping (one-pedal urban/suburban driving almost always under the control of ACC) and don't recall ever braking so hard that traction was lost and ABS activated. If traction isn't lost, ABS shouldn't be activated, so maybe your i3 wasn't losing traction during hard braking. Nevertheless, I'm surprised that your brake pedal can be pressed to the floor. That doesn't seem normal.

Click to expand...

I tried it again, "to the floor" was not accurate. It felt that way but it seems more like 4 inches of travel (I measured) before I can get the abs to kick in.

alohart said:

The maximum ambient temperature here these days is ~90º F. Our i3 cabin is comfortable with the A/C set to AUTO and the thermostat set to 74º F. However, we're comfortable with our apartment thermostat set to 77º F, so a thermostat setting in our i3 below 74º F would be uncomfortably cold for us. Nevertheless, it doesn't seem normal to have to set the A/C thermostat to 62º F to maintain a cabin temperature of 68º - 70º F.

Click to expand...

Thanks for the info!

frictioncircle said:

Hello sandi –

Congratulations on your new ride and welcome to the forum!

Click to expand...

Thank you!

frictioncircle said:

Most of my driving experience is with BMWs and the amount of pressure / pedal travel to reach ABS engagement on my 2014 i3 feels about the same as the other BMWs I've owned.

A properly-serviced i3 should have a brake fluid change every two years. If the prior owner neglected service, lived in a humid environment, and opened the brake fluid reservoir then perhaps the brake fluid could have absorbed some moisture (leading to a soft pedal) but otherwise what you describe is not normal.

If the pedal truly "goes to the floor" then there may be a brake fluid leak or failed master cylinder. In five years on this board I've not heard of either of those happening in an i3.

Click to expand...

I tried it again, "to the floor" was not accurate. It felt that way but it seems more like 4 inches of travel (I measured) before I can get the abs to kick in. The pedal seems to have a spongy feel. I think I'll have the brake fluid flushed. Though according to BMW service records it was done only 14 months ago.

frictioncircle said:

Regarding A/C, I've found the one fitted to the i3 to be very capable in exterior temps above 110°F (dry). Needing to set Auto 62°F with exterior temps around 90°F doesn't sound right. Note that I have all windows tinted, including front and rear, which I think is a requirement for this car in a hot environment.

Click to expand...

Thanks for the info. It appears the last owner had the windows tinted on this car as well.

frictioncircle said:

Was your purchase a CPO from a BMW dealer? If so, I'd have some questions for the service department.

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I picked this up at a random, local car lot. It still has over a year left on the warranty.

jadnashuanh said:

One thing that may be counterintuitive is the fan...on the i3, it's sort of an aggressiveness adjustment, so first thing, move it up a couple of notches.

Click to expand...

Ahhh! That seems to be it! I guess I should read the manual. This is the first car I have seen where you can control the AC fan in "Auto" mode. Thanks!

Pahaska said:

I'm in Austin, with a new-to-me for 1 1/2 months 2018. I set the AC at 74 degrees and find that the AC is great in comfort mode at 108 degrees and acceptable in Eco Pro at up to maybe 105. I do try to get my driving in before noon. That's as hot as I have experienced so far this summer. We have at least another week of over 100 every day.

I'm more concerned with the resisitive heat (Rex) next winter impacting the mileage. Wish I had the heat pump.

Click to expand...

I live in PA, and the heat definitely takes a major toll on range in my LEAF.

Thanks all!

Pahaska said:

I'm more concerned with the resisitive heat (Rex) next winter impacting the mileage. Wish I had the heat pump.

Click to expand...

Is there any info out there on how fast you can drive with the (resistive) heat on in a REx and still maintain constant state of charge with the generator?

sandi said:

Pahaska said:

I'm more concerned with the resisitive heat (Rex) next winter impacting the mileage. Wish I had the heat pump.

Click to expand...

Is there any info out there on how fast you can drive with the (resistive) heat on in a REx and still maintain constant state of charge with the generator?

Click to expand...

I have it coded to fire up the Rex anywhere under 75% and I never intend to let the battery get low enough that I would have to serously worry. Fortunately, It usually doesn't get really cold here in central Texas., mostly sweater or light jacket days.

Getting the ABS to kick in is not directly tied how far the pedal is pushed. It kicks in when it detects a wheel starting to lock up. This will be different pedal push distances depending on weather, speed, tire condition, road surfaces, turning or going straight..... Despite the skinny tires which certainly don't help, the stopping distance is pretty good for these cars.

Do you have the 19" or 20" wheels on the thing? And, if the 19", are the rears wider than the front?

FWIW, the size of the tire patch is determined by the air pressure and the weight on the wheels. Tall, narrow tires would have the same contact patch as a wider, shorter one IF the air pressure was maintained. The difference is the shape of the contact patch, not its area. So, a taller, narrow tire/wheel will have more contact patch aligned for forward/rearward forces than cornering forces. It also will depend on the road composition, any oil, sand, crud on the surface, and the age and type of tire on the vehicle.

Personally, I think the reasons BMW chose for the tires they did were justified. Maybe not as much today with the much larger battery pack, but certainly for the original one. A wider tire makes it harder to get the tight turning circle that wanted for their city car, too. The narrower tire/wheel assembly produces less drag. And, they chose to forge the wheels rather than the more common cast them so that they could be lighter since forging them makes them stronger, and thus don't need to be as thick.