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Discussion Starter · #1 ·
I took my first long-ish trip. 157 miles. Not even a stop for a charge, but I learned something:

If using ABRP to plan your charge stops, it's really a good idea to stick to the speed limit.

I planned the route with ABRP and set it to have 200 pounds extra weight in the car. Just before I left, I charged the car to 100%. ABRP said I would get to my destination with 29% battery.

I got on the road and generally ran about 3 mph above the speed limit with the A/C set to 72 degrees (it was about 80 degrees and humid outside). That meant at least half of the trip was with the cruise control at 78 mph. I guess you could throw in the East Texas hills as a factor as well.

I arrived at my destination with 25% charge per the MyChevy app. I was a little surprised by that result, so I went back into ABRP, set the speed to 104%, and recalculated the route. Sure enough, it said I would arrive with 25%.

I'm taking a trip this weekend...ABRP says I'll get there with 10% battery. I'll be sticking to the speed limit!
35553
 

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2020 Bolt EV LT
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Good idea to stick to the speed limit, but you may have to drop below that if you have a significant headwind (unless you've already factored that in on ABRP). Pay attention to the Min Range display after you pass the halfway point.
 

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Discussion Starter · #3 ·
I drove home with the cruise control set at the speed limit (55 to 75 mph) and the A/C set at 71° (outside temperature was 85 degrees with high humidity). ABRP showed that I would get home with 32% battery remaining. I got home with 33%. Pretty good.

My next trip will be about 385 miles and will require at least 2 charge stops according to ABRP. It's interesting to see that running faster and charging more actually provides for the shortest total trip time by more than 20 minutes.
 

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I drove home with the cruise control set at the speed limit (55 to 75 mph)
FYI, your actual speed was below the speed limit. Manufacturer's face hefty fines if the speedometer reads lower than your actual speed. So all manufacturers calibrate the speedometer to read higher than your actual speed. Seems to be around 3 MPH high around 65 MPH for every vehicle I've checked.
 

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Discussion Starter · #5 ·
Good point. I've noticed the same thing on my other vehicles. I didn't seem to be impeding traffic, so I didn't think about that. I'll check it out.
 

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FYI, your actual speed was below the speed limit. Manufacturer's face hefty fines if the speedometer reads lower than your actual speed. So all manufacturers calibrate the speedometer to read higher than your actual speed. Seems to be around 3 MPH high around 65 MPH for every vehicle I've checked.
Only noticed a 1mph difference between the Bolt's speedometer and my GPS at 55mph. Granted it's not a super-accurate GPS but 3mph sounds high to me.
 

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FWIW I did a calibration cycle within the Car Scanner app (using the bluetooth VeePeak OBDII adapter) in my 2021 Bolt and it came out +0.5% so in my case it is almost dead on (with Michelin CrossClimate2 tires at 42 PSI).
 

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in my 2021 Bolt and it came out +0.5% so in my case it is almost dead on (with Michelin CrossClimate2 tires at 42 PSI)
0.5% would be much closer than I've seen. But I wonder if your tires are a little bit larger O.D. than stock, making it closer. Worn tires (smaller O.D.) will also make the speedo read even higher than actual. It's be nice if the speedo would just self-calibrate using the GPS.
 

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0.5% would be much closer than I've seen. But I wonder if your tires are a little bit larger O.D. than stock, making it closer. Worn tires (smaller O.D.) will also make the speedo read even higher than actual. It's be nice if the speedo would just self-calibrate using the GPS.
My experience with radar signs suggests the Bolt is closer than 3 mph, probably more like 1 mph.
 

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Well the OEM Michelin Energy Saver A/S Selfseal and CrossClimate2 tires both show 815 rev/mile (25.5" diameter) on Tire Rack. Not sure if a few more pounds of air would cause the circumference to grow enough to make a difference.
 

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Discussion Starter · #11 ·
I checked it out, today, with 40 psi in the tires. I set the cruise at 70 and my GPS hovered around 69.5. That's way closer than any of my other cars.
 

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Hmm... I'll have to check mine. I just realized that I had checked the speed vs. GPS during a trip last weekend and it was about 2.5 miles off... while we were driving in my wife's car. Doh!
 

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Discussion Starter · #13 ·
I took a road trip this weekend and found that my speedometer actually reads a little slow at 80 mph! With the cruise set at 80, my GPS was hovering around 80.5 mph.
 

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Finally checked mine and sure enough, it's almost perfect. I'm wondering if the Bolt is using the GPS to self calibrate. Has anyone with different size tires from stock checked if the speedo corrects itself?
 
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