Chevy Bolt EV Forum banner
  • Hey Guest, welcome to ChevyBolt.org. We encourage you to register to engage in conversations about your Bolt.

Which commute is better? A shorter stop-and-go 25-35 mph or longer more steady 45-50 mph?

6068 Views 69 Replies 18 Participants Last post by  jefro
I have been wondering on my daily for BEV.
I know which one is better all ICE - of course 45-50 mph, but for EV - well, not so sure.
While one would say lower speed less energy use, holds true, it is not so good anymore when you use regen often.
Regen is, what, about 60% efficient? Give or take a few, or a dozen% as it depends how you are slowing down.

The trip is flat.
Option 1: 11 miles, 27 minutes (stop and go, 25-35 mph)
Option 2: 13 miles, 27 minutes (much more steady speed, 45-50 mph)

If I could roll, without frequent stopping, I would always opt for the shorter one, but that is not the case.


So, any science supported answers?
I tried to do some math, but I gave up - too many variables and I did not have enough data to account for braking (regen), meaning time, distance, and power of braking.
1 - 3 of 70 Posts
I have been wondering on my daily for BEV.
I know which one is better all ICE - of course 45-50 mph, but for EV - well, not so sure.
While one would say lower speed less energy use, holds true, it is not so good anymore when you use regen often.
Regen is, what, about 60% efficient? Give or take a few, or a dozen% as it depends how you are slowing down.

The trip is flat.
Option 1: 11 miles, 27 minutes (stop and go, 25-35 mph)
Option 2: 13 miles, 27 minutes (much more steady speed, 45-50 mph)

If I could roll, without frequent stopping, I would always opt for the shorter one, but that is not the case.


So, any science supported answers?
I tried to do some math, but I gave up - too many variables and I did not have enough data to account for braking (regen), meaning time, distance, and power of braking.
If you really can keep the speed steady, below 50 mph, and the longer route doesn't have much in the way of hills or strong winds, you probably will eke out a tiny bit better efficiency. Any more than 50, though, and aero drag will quickly push the longer trip into negative territory.

EVs and hybrids are generally better in-town at low speeds, even with stop n go, than at higher steady speeds. Low speeds keep the aero drag, especially, down, and EVs recover a good bit of the accel energy with regen (use L range to maximize that in a Bolt). Even in a hybrid like a Prius, you'll see a higher MPG rating in city driving (low speed, using the electric mode more, recovering energy with regen, etc.) than on the highway (higher, steady speed, constant power draw with little chance for regen). In the olde dayze, with first-gen EVs like the EV1 and Honda, we used to call freeway driving (constant high speed) the EV-killer mode, because the range would be so much less than when running around town.

Craziest thing I ever saw was with a Corolla FX16 I used to have. EPA rated at something like 24/28. I normally got 25-26 mpg in it around town (suburban type driving, up to 45mph or so, signals every 1/2 mile or so with no effective coordination) and 28-30 on the freeway (65-75mph cruising). On one vacation, though, we did a day's touring around the wine country, mostly on back roads, plenty of hills but little traffic and speeds generally under 40 mph. Filled up the day before, for the touring, and after returning to the hotel, for the next day's trip home, and the tank mileage for that was 50 mpg!
See less See more
I'm really surprised that anyone with much experience in the Bolt has any reason to think that option 2 might be more efficient. In L and with the regen paddle, it's very clear to me that option 1 is more efficient. If I were to operate the Bolt as a taxi in a downtown area or residential neighborhood where the speed limit is 25 and I sometimes go 35, I would expect a range on a full charge of about 500 miles.
The difference in distance offered by the OP is very small, and the obvious time difference considerable. I'd expect almost anybody to choose #2 even if it were much worse from an efficiency standpoint. In fact, if (and I made this caveat clear I hope) the speed in #2 actually does stay under 50 (preferably under 45 - what's the speed limit?), I'd expect efficiency to be pretty good. Not the best a Bolt can do, but pretty good - well into the 4+ miles/kwh band if HVAC isn't cranking. Where I live, that's the best I can hope for.

True, if #1 were truly low speed, stop & go, with very little go (i.e. traffic isn't drag-race start only to hit the brakes again hard; I've seen that), the theoretical range might approach the maximum the GOM opines. Few people would ever get that, at least frequently. You might get it on one trip when all the stars aligned, like that crazy trip I had in the Toyota. It could happen. So if you're looking for a personal best, once, #1 might be the way to go. Just don't expect it to work often; LOS E-F traffic flow like that is fundaamentally unstable. And mentally disastrous. For repeatable good, #2 is more likely to deliver.
See less See more
Oh, I see now. I think this is more of a theory than reality, but well, they got Kona to do over 600 miles... so who knows.



No?
Watch me! Yeah, that is my problem. I love the torque and... I buy tires too often.
Ages ago, I ran a study that used chase cars with lidar (this was before several modern methods) to study how people drove on freeways. Found that in LOS F conditions (stop & go) conditions, speeds as high as 60 mph were briefly recorded, and acceleration rates from SUVs that (briefly) approximated drag strips. You wonder why gas mileage is so poor in congested traffic?
1 - 3 of 70 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top