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As you point out, driving electric is already super cheap from a cost per mile basis. The cheaper it is per mile for me to drive, the less interest I have in modifying the vehicle or my own behavior to reduce that cost further.

That's the law of diminishing returns at play. A car that gets 25 MPG might consume 480 gallons in a year. Doubling the efficiency to 50 MPG, that car consumes 240 gallons, a saving of 240 gallons. Doubling the efficiency again to 100 MPG would take extremely costly engineering measures, but this time only save 120 gallons. Each doubling is much harder to achieve, yet saves only half as much as the previous doubling.

The only way I would have an interest in improving the efficiency of the Bolt is if there was a frequent trip that is just within the capabilities if only I made some relatively simple mod. The other time I would have an interest is when considering things like adding additional storage. I'd choose a hitch mounted box rather than roof, because I want the thing that isn't going to harm efficiency (and likely improves it).
 

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2021 Bolt LT, 2021 Kona EV SEL
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It appears likely a hitch mounted box could improve your efficiency/range. How much is undetermined since a controlled and repeatable test hasn't been performed.

How important achieving better efficiency is to you determines to what lengths you will go through to achieve it.

Physics pisses me off, I get the wheel covers, but adding stuff to the back shouldn't do anything. Why fluid dynamics, why?!
 

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Physics pisses me off, I get the wheel covers, but adding stuff to the back shouldn't do anything. Why fluid dynamics, why?!
Having the air "stick" to the back end causes drag. Adding parts that cause the airflow to make a clean break from the back can reduce drag. It's the functional reason for the spoiler at the top of the rear window. That civic is like a full body spoiler.
 

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Physics pisses me off, I get the wheel covers, but adding stuff to the back shouldn't do anything. Why fluid dynamics, why?!
The front is less important than the rear. Any bulbous front is pretty good at punching a hole in the air. Getting the air to exit without rolling around behind the car is more important.
 

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Having the air "stick" to the back end causes drag. Adding parts that cause the airflow to make a clean break from the back can reduce drag. It's the functional reason for the spoiler at the top of the rear window. That civic is like a full body spoiler.
A design that causes the airflow to come back together before that clean break is even better...but pretty bad from a packaging standpoint.
 

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Physics pisses me off, I get the wheel covers, but adding stuff to the back shouldn't do anything. Why fluid dynamics, why?!
The basic concept is easy. The vehicle displaces all of the air it's occupying, moving it around the vehicle as it moves forward. Immediately behind the vehicle is where it was just a moment ago, meaning it leaves a vacuum behind it; a region where nothing exists because there hasn't been enough time for something (air) to fill it up. That vacuum is pulling the car backwards because it pulls everything from all directions.

A tapered design allows that void space behind the vehicle to not develop because air is continually attached to the surface. That's called laminar flow, when air is "attached" to the shape of the vehicle. Airplanes are designed to have laminar flow (tapered). A stall is when air becomes unattached, creating a low pressure (vacuum) behind the wing.

That's an oversimplification and not entirely accurate, but gives a general principle of what's happening.

The crazy thing to imagine is none of that matters in space or the moon. There's no atmosphere and no pressure, so driving with an enormous parachute on the moon, it would just drag on the ground. You could design a vehicle like a 10 foot brick wall and it would be just as efficient as something sleek.
 

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Would be nice to have a 3d insert for the older oem wheels.
What do you mean older OEM wheels? Mine are the OEM wheels from 2017 and those inserts I posted are designed for them.
Tire Wheel Vehicle Automotive tire Locking hubs
 

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Discussion Starter · #194 ·
What do you mean older OEM wheels? Mine are the OEM wheels from 2017 and those inserts I posted are designed for them.
View attachment 42564
Age aside those are the ones I’m talking about.
Woohoo! Someone made inserts!
 

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That is easily accomplished!!
Drive slower and slower until you achieve that number! (y)

But please, don't be on a highway in front of me.:mad:

I can afford the electrons to drive like a normal person. :cool:
62 slowest I am will to drive, have changed the tire pressure to 42 see how that does. Been throwing around the idea of 3d printing some piece's to fill up the hole's in the stock wheels, 1200 for new wheels bit to much.
 

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62 slowest I am will to drive, have changed the tire pressure to 42 see how that does. Been throwing around the idea of 3d printing some piece's to fill up the hole's in the stock wheels, 1200 for new wheels bit to much.
62 mph on the interstate is perfectly fine, perfectly normal.....:rolleyes: Think of the pennies saved (y)

Yeah, those wheels will never have a 'pay back'. (If their 'improvement' can even be measured)
Those 3D printed inserts didn't look great as for fit and how they are secured is not defined.

So my idea,
The thinnest Lexan sheeting you can get at the Depot, cut to circles the size of the wheels.
Secured with,,, 5 large ty-raps going thru twin holes at each spoke of the wheel. Maybe small strips of thin stick-on foam tape under the Lexan where the ty-raps pull against the wheel.

Ideally, the center hole of the wheel could have a machined 'plug' that is threaded on both sides to secure it to the wheel on the inside and thru the Lexan on the outside to have the disc centered before cinching down the ty-raps.

Clear so they would not be noticeable until very close to the car.
Installing while the wheels are on the car is a chore, but leave them on for a few thousand miles and try to measure any difference.

And while working with the Lexan make rear wheel fender skirts that attach to the plastic surrounding the wheel opening with 3" strips of Industrial Velcro. You can skip the wheel covers on the back!
Are vortex generators still a thing? I can see clear ones stuck along the rear of the car on both sides and the top.

All these mods are 'stick ons' and can be removed easily. And they are light so should be not to dangerous if they 'remove' themselves while on the highway.
All these mods are for cars used at highway speeds. Not worth it for townie Bolts.

So, if you are getting 3.4 mi/kWh at 70 mph, stock, what would that number be with these mods?
Testing is always tough to nail. At least around here the temps are changing quickly and strangely, for some unexplainable reason....:(

I no longer have access to a shop to build stuff like this, so I'm all talk, no action....:cautious:
So please, someone, to your shop!!!
 

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Discussion Starter · #198 ·
I’ve gotten far larger data sets now to confirm the range increase

Many thousands of miles, first one way then the other.

the difference between having the trunk and not having it is remarkable.

without I get 4.2 ish

with I get 4.6-4.7 ish

this is largely highway road trip mileage.

currently I Have 1200 miles on the latest trip counter which agrees with previous counters.

I am also running other modifications as I have noted, 40-45psi in the tires, ev01+ wheels, Michelin self sealing EV tires, and obviously, the trunk.

I have a lithium iron 12v battery but I don’t think that plays much into it.

I have a lot of stuff loaded in the car currently. Couple hundred pounds of crap probably.
 

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View attachment 42285
I’m getting 4.9 mi/kwh right now
I drive in D, use mostly the paddle for stopping.
Here are my mods:
-Michelin energy saver self sealing tires
-45 psi on all four tires
-Fast EV01+ wheels
-Hitch mounted trunk modified to sit closer to bumper.
-Ecohitch with gussets added to frame
-Battery recall (helped range, not mile/kwh)
-Vehicle reported average speed 27.7 (this is the average speed for entire time the vehicle has been running while the average was being calculated, Idk when last I reset this, maybe 10-20k ago) I usually go 55-65 on highway. And it still produces this average.
-location arizona

before hitch mounted trunk: (observe mi/kwh)
View attachment 42282

after hitch mounted trunk: (observe mi/kwh)
View attachment 42281
Edit: 1200 miles approx on average calculation and I am at 5.0 miles/kwh now. Much of this trip was a drive between Vegas and Phoenix, so lots of highway speeds.
What did you do to mod the hitch mounted trunk to get it closer to bumper. Pics would be nice.
Thanks
 

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I ran across a DIY alternative to the box, which would allow options of making it even more form fitting to the Bolt. This guy built a similar box for a Scion XA, but the same method could be used.
 
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