Help me eco mod my i3!

[milo]

I have a 2014 i3 with about 75k miles but a brand new battery. I've already ordered new LED high beams, and it has the 429 turbine wheels. I'm planning on getting the Ecopia ep500s which are summer tires to replace my current ep600 all seasons when those break down. I've also reduced the weight by a few pounds not by making the car lighter weight but getting a new lighter backpack and bag stuff. also doing a few other things that I'll bullet point now

- LED High beams
- Summer EP500 tires
- Smaller stick antenna
- Sequential turn signals that are about 3 oz lighter and less power intensive
- Removing the back "E-Drive" & "i3" badges for 3oz less weight and a flatter back
- Vinyl stick on front license plate. smoother front and less weight
- Might use white painters tape when I drive up to my lake home which is the longest trip I regularly make. about 65miles. 20 of those miles are city miles so it's less intensive on an EV

[Ecky]

I appreciate the vinyl license plate - I've never heard of such a thing.

Realistically, weight and electrical savings are going to be far less significant for economy than (visible) aerodynamic mods and lower rolling resistance tires. Many are reluctant to do visible aero mods on their vehicles.

For an i3, I'd wager the low hanging fruit will be wheel well covers and a kamm. The i3 has a relatively abysmal Cd of 0.30, due to basically being a brick, and any improvements here will be visible in range and efficiency.

[Ecky]

A quick Google search revealed this: https://www.mybmwi3.com/forum/viewtopic.php?t=534

First off, I like the i3. As a city car (say London within the M25) it makes a lot of sense. However, having driven both REx and BEV models both on 24h test drives using same commute I have come to the conclusion that it is not quite as efficient as it might be.

Around town, at or below 40 mph, aerodynamics have little impact on a vehicle's range.

This post is about basic aerodynamic drag so I'm not including the complexities of interference drag (e.g: between mirrors and bodywork or turbulence created by wheels) nor surface friction concerns or Lift induced vortices.

We'll stick to good old Bernoulli's principles and Frontal Area.

BMW claim the i3 BEV has a Cd (non dimensional drag coefficient - basically describes how the car's shape affects drag) of 0.29 and Rex has 0.3Cd - doesn't sound too bad until you multiply that by the frontal area: CdA

This makes a lot of sense as now you can compare a huge variety of cars side by side.

OK so that makes the CdAs for the i3:

BEV: 0.690 m2
REX: 0.710 m2

Now compare this with other cars like:

1990s Honda Insight (2 seater hybrid): Cd = 0.25 but CdA = 0.474
1999 - 2005 Audi A2 1.2 TDI: Cd = 0.25, CdA = 0.544
1980s Toyota MR2 (2 seater) : CdA = 0.539

So the i3 is about as aerodynamic as a 1990s Toyota Camry or Subaru Impreza!

Even the 1995 BMW M3 is better: CdA = 0.629 m2 and possibly my least favorite car (the 2004 Prius) is 0.580 m2

The best examples in the noughties seem to be the VW XL1 (2 seater) with CdA of 0.279 and the German Loremo prototype (2+2): CdA = 0.250 m2

Sadly the XL1 is no People's Car and might better be re-badged the EB XL1 (a cheap £100k Bugatti !) Sadly Loremo still seems to be in the doldrums.

A little tip from driving my Active E for two years in Southern California and 45k miles later...

If you need to go somewhere and you barely have enough charge to get there, try this method, it really works:

1) Drive slower - The faster you go the more drag you'll get.
2) Draft behind a semi truck, not too close to be dangerous but 3 or 4 car length behind.
3) Drive slow uphills and let it recharge down hills.

If you have a full charge and only need to go somewhere close, forget all that and enjoy the ride.

Cheers,

As the second quoted poster suggests, there are things you can do to mitigate the poor aerodynamics. Drag goes up exponentially with speed, and since you're starting with an already large drag number, you can get a ton of extra range by driving 10-20mph slower, or by using large vehicles to shield you from wind on the highway.

[redpoint5]

Curious what prompted the new battery?

By far the most drastic "mod" to increase range in an EV is simply driving slower. I know you'll probably get run over in CA if you aren't bumper to bumper with the guy ahead.

Weight isn't going to make much difference; not measurable anyhow. Your range savings by weight reduction is going be feet, not miles.

Use seat heaters instead of cabin heat; seat heating is very efficient.

There might be a tiny benefit replacing the 12v battery with a LiFePO4, but only if it doesn't get exposed to freezing temperatures.

Aero treatments mentioned by Ecky are the next thing on the list after simply driving slower though.

Here's the other thread on the i3;
https://ecomodder.com/forum/showthre...ics-37645.html

Bob Wilson also had (has?) one.

[freebeard]

Needs more pictures.


https://external-content.duckduckgo....3d4&ipo=images

The one in the lower left? Are they directional (lefts and rights)?

Nothing beats a full boat tail. Practically, a boxed cavity comes close. The ideal:



The real:

[bwilson4web]

Yes, I bought a backup, 2017 BMW i3-REx for my Tesla. Then I took it to a ribbon cutting celebration for ChargePoint Fast DC chargers only to have someone back into the passenger side door. I dropped it at the BMW (Be More Waiting) body shop this morning.

My plans:

• Clear windshield film - gravel impacts lead to expensive replacement. The film should block air leaving to a small pit, not an expanding crack.
• Recling passenger seat - so it can become 'Hotel BMW'. A water and bug resistant tent with floor panels will minimize hotel/motel costs. Camp out at a free L2 charger <GRINS>.
• Aero wheel covers - a significant source of drag, the spokes work like fan impellers. At least one credible SAE paper shows this is a significant drag source.
• Aero mud guards - one in front of each wheel and possibly one behind to minimize the head-on wheel drag. If you don't let the air come to a complete stop, the drag goes down.
• Tuff, ribbon, smoke testing rear body - mine has a 2" receiver so I'll make videos showing what the air is doing behind and under the car. Then I'm can make cardboard, bodies to measure their effects.

Accurate benchmarks, A-B-A testing, will keep me from fooling myself.

Bob Wilson

[milo]

Originally Posted by bwilson4web

Yes, I bought a backup, 2017 BMW i3-REx for my Tesla. Then I took it to a ribbon cutting celebration for ChargePoint Fast DC chargers only to have someone back into the passenger side door. I dropped it at the BMW (Be More Waiting) body shop this morning.

My plans:

• Clear windshield film - gravel impacts lead to expensive replacement. The film should block air leaving to a small pit, not an expanding crack.
• Recling passenger seat - so it can become 'Hotel BMW'. A water and bug resistant tent with floor panels will minimize hotel/motel costs. Camp out at a free L2 charger <GRINS>.
• Aero wheel covers - a significant source of drag, the spokes work like fan impellers. At least one credible SAE paper shows this is a significant drag source.
• Aero mud guards - one in front of each wheel and possibly one behind to minimize the head-on wheel drag. If you don't let the air come to a complete stop, the drag goes down.
• Tuff, ribbon, smoke testing rear body - mine has a 2" receiver so I'll make videos showing what the air is doing behind and under the car. Then I'm can make cardboard, bodies to measure their effects.

Accurate benchmarks, A-B-A testing, will keep me from fooling myself.

Bob Wilson

Have you looked at the YouTuber Bmwi3diy? he does lots of camping in his 15' rex, And the reclining seat idea reminds me a lot of the urban suite idea they had at CES2020.

[milo]

Originally Posted by freebeard

Needs more pictures.

The one in the lower left? Are they directional (lefts and rights)?

They are the bottom left, it goes 427 (grey monotone) 428 LA style multi-spoke 429 Turbine dual tone then the 20 inch 430 which sucks in every way since it's less efficient and heavier. 427 & 429 are best

[freebeard]

Thanks. IMHO the 427 would be best (closest to a blank disk) but not enough difference to bother.

In my Superbeetle, the shotgun seat has been replaced with a deck. If I have a passenger they get a lot of leg room.

[redpoint5]

Originally Posted by freebeard

In my Superbeetle, the shotgun seat has been replaced with a deck. If I have a passenger they get a lot of leg room.

What kind of MPG are you currently getting in that Superbeetle?