[Zoomit]

I was playing around with some acceleration models and thought this forum might be interested in the results. I created the models based on Car&Driver test data:

2017 Bolt EV - http://media.caranddriver.com/files/2017-chevrolet-bolt-ev-test-review-car-and-driverchevroletboltev2017.pdf
2017 Volt - http://media.caranddriver.com/files/2017-chevrolet-volt-premier-test-review-car-and-driverchevroletvolt2017.pdf
2014 Spark EV - http://media.caranddriver.com/files/2014-chevrolet-spark-ev2014-chevrolet-spark-ev-mar-2014.pdf
2014 Model S 60 - http://media.caranddriver.com/files/2014-tesla-model-s-60-full-test-review-car-and-driver2014-tesla-model-s-60.pdf
2014 i3 - http://media.caranddriver.com/files/2014-bmw-i32014-bmw-i3-comparo.pdf
2011 Volt - http://media.caranddriver.com/files/2011-chevrolet-volt-full-test2011-chevrolet-volt-complete-specs-and-performance-data.pdf

The results don't perfectly match the C&D data, but it's pretty close and well within the normal variation due to test methods and conditions.
Note 1: The 2015-16 Spark EV's have a 3.87 final drive ratio, vs 3.17 in the 2014 Spark EV's.
Note 2: The S 60 is the original version with the smaller ~60 kWh battery.
Note 3: The i3 is the BEV with the lighter 60-Ah (22kWh) battery.

There are a few nuances to pull from the charts, but my biggest takeaways are:
1) The Bolt EV will accelerate decently right up to 93 mph. Hitting that speed limiter will be noticeable as the acceleration falls from 0.13g to zero. This jerk is probably atypical, as many cars aren't accelerating as much when they hit their rev-limiter or they are drag limited.
2) The Bolt EV acceleration does appear to be optimized for better highway acceleration, as indicated in interviews with GM personnel.
3) At highway speeds, the Bolt EV will respond almost as well as the old S 60.
4) I'm bummed that C&D never tested the 15-16 Spark EVs, because that's what I drive.

 

[cab]

Cool - and nice visual of what I have felt test driving the i3, Volts and Tesla.

 

[hvacman]

Great analysis! One comment. Most of the vehicles reviewed have conventional 1-motor with rare-earth PM magnets or induction motor which create a relatively-linear g vs speed fall-off. The Gen 2 Volt's acceleration characteristics are unique in that it has two electric motor "gears" - two motors that change their relative power contributions based on speed. The rare-earth PM motor is the low-speed/high torque motor and the ferrite PM motor is the high-speed low-torque motor. This gives maximum torque at 0-40, with a strong fall-off at higher speeds, giving the much steeper g vs speed curve slope at higher speed.

http://www.greencarcongress.com/2015/04/20150423-voltec.html

 

[Qinsp]

The biggest selling affordable Green Cars, are the Leaf EV, and Prius Hybrid.

This is what makes the Spark EV, Volt, and upcoming Bolt significant. They broke the mold of the middle class driver's "green" car being a slug.

Both the Model S and BMW i3 are more expensive models, and in the case of the i3, not a big seller.

 

[hvacman]

This is from the SAE paper on the Bolt propulsion system design.

The Bolt axle ratio was optimized in the following priorities, highest first:

Range
Passing acceleration (highway-speed acceleration)
Launch (low-speed acceleration)
Grade ability (how steep a hill it can climb)

 

[DonC]

Great job with the graphs. Nice. Thanks for posting.

 

[Qinsp]

This is with my kid's crayons editing a pic to add the quickest version of the newest Prius, $32,700, 3100lb, 121HP for a 25.6 lb/hp at the brochure.

The 2011 Volt is 25.5 lb/hp.

Somebody is not telling the truth. Either Chevrolet or Toyota.

 

[Ladogaboy]

This is with my kid's crayons editing a pic to add the quickest version of the newest Prius, $32,700, 3100lb, 121HP for a 25.6 lb/hp at the brochure.

The 2011 Volt is 25.5 lb/hp.

Somebody is not telling the truth. Either Chevrolet or Toyota.

View attachment 122537

Other factors could come into play. The first thing I think of is that Toyota tends to combine the ICE and motor power numbers, but if I remember correctly, you can't actually get 100% power from both at the same time. So even though they claim 121 hp, the car might only be producing a peak 100 hp. That would be the equivalent of GM marketing the Volt as just over 200 hp despite the fact that the ICE only rarely contributes power directly (mechanically) to the drivetrain.

 

[Loboc]

"Hitting that speed limiter will be noticeable as the acceleration falls from 0.13g to zero. This jerk is probably atypical, as many cars aren't accelerating as much when they hit their rev-limiter or they are drag limited. "

Some large-engine small vehicles have this issue. I had a 2002 Dodge Dakota pickup with the 4.7l V-8. It was quite noticeable (like an anchor was being thrown out) when the 100mph limiter was hit as the engine was still pulling strong.

 

[Ladogaboy]

"Hitting that speed limiter will be noticeable as the acceleration falls from 0.13g to zero. This jerk is probably atypical, as many cars aren't accelerating as much when they hit their rev-limiter or they are drag limited. "

Some large-engine small vehicles have this issue. I had a 2002 Dodge Dakota pickup with the 4.7l V-8. It was quite noticeable (like an anchor was being thrown out) when the 100mph limiter was hit as the engine was still pulling strong.

That actually happens with manual sports cars a lot. Some are better than others, but typically, you are still near max power when you hit the rev limiter for several gears (2nd and 3rd in particular). Depending on how the rev limiter is set, you can bounce against that ceiling pretty hard.

 

[Zoomit]

That actually happens with manual sports cars a lot. Some are better than others, but typically, you are still near max power when you hit the rev limiter for several gears (2nd and 3rd in particular). Depending on how the rev limiter is set, you can bounce against that ceiling pretty hard.

Great example. I don't think it'll feel like throwing out an anchor, it'll just be distinct.

Going back up to the first graph, the forward jerk from hitting the 93mph limit in the Bolt could feel like the aft jerk you get when driving steady and instantly mat the throttle at the following speeds:

'11 Volt*: 66 mph
'14 Volt*: 71 mph
'14 Spark EV: 73 mph
'14 i3: 78 mph
'14 Model S 60: 94 mph

These would be about the same acceleration, just different directions. Doing this is only possible with an electric motor, with it's instantaneous response.

*If the IC engine in the Volts are needed for max acceleration at those speeds, then the jerk WILL NOT be the same.

 

[PodCat]

The Bolt does 0-60 in 6.3 seconds.

Do you, by chance, know what the fastest production car in 1977 -- the Porsche Turbo Carrera -- came in at?


6.9 seconds.
The Chevy Corvette was second at 7.4 seconds.

6.3 seconds is %#€!ing amazing.


http://www.businessinsider.com/moto...ce=Viber&utm_medium=Chat&utm_campaign=Private