[Electro]

Been reading a few articles about the Chevy Bolt having terrible aero in the sense of it having the highest drag coefficient among it's competitors. Apparently GM traded off aerodynamics for utility and space when designing the Bolt.

Stuart Norris, the EV's design team leader, himself calls the Bolt a "Disaster for aero."

The car has a drag coefficient (Cd) of 0.32. By comparison, the Toyota Prius has a Cd of 0.24, while the Tesla Model 3 will record a downright-slippery 0.21 figure.

The Bolt's design team tried to compensate for the model's less-than-optimal aerodynamics with a spoiler and underbody paneling, as well as grille "shutters" that close at certain speeds. Designers cut weight by using aluminum for the car's doors and hood, while the A-pillar radius was also tweaked. All told, designers tested a half-dozen versions of the Bolt in wind tunnels as the design team further fine-tuned the vehicle's shape.

 

[DucRider]

The aero isn't "terrible", nor is it the highest among it's competitors.
They did have to work much harder with the hatchback/small wagon form factor to get decent results.

drag coefficient:
Bolt .312
LEAF .32
i3 .29
Soul EV .35
e-Golf .28
B-class .26

 

[Electro]

Wellp.. that discredits the article ..

 

[Bazinga]

It's not really that much of a difference after seeing the numbers lined up and I'd rather have more cargo space than amazing aerodynamics. This is as good as they were able to make the Bolt and at city speeds, it shouldn't really affect the fuel economy. Utility and practicality wins!

 

[Breezy]

Yeah, the "quote was taken out of context." He was saying that vehicles with that form factor are inherently a "disaster for aero," hence the team's efforts to get it down to 0.32.

 

[Zoomit]

The quote was definitely taken out of context and turned into clickbait, but the Bolt EV's high speed efficiency is inferior to most EVs.

At freeway speeds, especially at 75+ mph, the aerodynamic drag force is the predominant force the drivetrain must overcome. The highway EPA numbers don't realistically reflect the car's efficiency at these speeds. The best parameter to compare cars is not the coefficient of drag (Cd), but rather the aero drag force. You'll see aero drag force represented as CdA because it's calculated by multiplying Cd by the vehicle's frontal area (A).

Some EVs have high Cd but low A, like the Fiat 500e. Others have low Cd but large A, like the Tesla Model X. The Bolt EV has both above average Cd and above average A. This means the Bolt EV CdA compares unfavorably with other EVs.

Here're my CdA (sq ft) estimates for many EVs:
Soul EV......9.1
smart ED....9.1
Bolt EV.......8.0
LEAF..........7.8
Spark EV....7.5
i3.............7.3
FFE...........7.0
B250e.......7.0
500e.........6.8
Model X.....6.7
e-Golf........6.4
Model S.....6.2
Model 3......5.0

The source numbers are taken from here: https://teslamotorsclub.com/tmc/media/20160507-bev-comparison.114929/

The only ones worse than the Bolt EV are rolling boxes; a little one (smart ED) and a larger one (Soul EV).

For those looking to compare the Bolt EV with the Model 3, the Bolt EV may have 60% (!!) more aero drag than the Model 3. This might translate into 30% less range than the Model 3 at 75mph. That could be a difference of 50 miles.
Bolt EV: 125 mi
Model 3: 175 mi

This discrepancy highlights one likely reason why GM isn't investing in a long range, fast charging infrastructure. Their BEV is not optimized for long range travel. Will the Bolt EV be an effective suburban runabout, absolutely; but expecting the Bolt EV to be a time-efficient cross country cruiser is misplaced.

 

[eops]

If GM makes an effort to have charging stations spread out enough then they'll have some luck, but fortunately that's already happening without the help of car makers.

Overall though people will be looking for a well rounded product and the way things are shaping up the Tesla might just win them over (as much as I hate to say it)

 

[Oldguy71]

Someone wrote earlier that the side view mirrors are the bain of aerodynamics. When will auto makers start mounting wide angle cameras on the outside of the sides of cars and small to medium screens on either side of the binacle in front of the driver. It may be a cost factor but once you started to acclimate to them I have to believe that safety would improve and aerodynamics would also.

 

[DucRider]

Someone wrote earlier that the side view mirrors are the bain of aerodynamics. When will auto makers start mounting wide angle cameras on the outside of the sides of cars and small to medium screens on either side of the binacle in front of the driver. It may be a cost factor but once you started to acclimate to them I have to believe that safety would improve and aerodynamics would also.

Automakers would love to do that (Tesla is at the forefront), but the NHTSA will not approve them.

They approved the camera rear view mirror on the Bolt, but only because it can be toggled to the traditional mirror with the flip of a switch.

 

[Oldguy71]

Does anyone why our goverment and it's multitude of agencies can't get with the program? I thought they were elected to work FOR us.

Sorry for the rant but sometimes they just baffle me!

 

[Zoomit]

http://spectrum.ieee.org/cars-that-think/transportation/advanced-cars/cameras-instead-of-mirrors-not-so-fast-says-experts

The technology is there but it must be compatible with humans and our habits and expecations.

 

[Electro]

Didn't China already start using this ? I can't remember on which vehicle but I heard they were possibly the only market that would have gone through with it

 

[eops]

Didn't China already start using this ? I can't remember on which vehicle but I heard they were possibly the only market that would have gone through with it

That might be just because of their regulations as from market to market it differs, so while it might work in China right now and comply with what it has to, on a global level it might be years behind.

A lot of companies have been testing fully self driving vehicles for a while, Google, Audi, etc, so soon enough we'll see something fit for our roads.

 

[Zoomit]

A lot of companies have been testing fully self driving vehicles for a while, Google, Audi, etc, so soon enough we'll see something fit for our roads.

Actually, side cameras and autonomous driving technology are quite different. The latter is concerned with collecting and providing data to a computer for its decision making, while the former needs to provide data to a human that is compatible with current driver experience.

 

[Electro]

As it is people are struggling with this autonomous technology... which for some reason I think would be proven to be easier than side mirror cameras. It's just society today.

 

[Sean Rarey]

Hum, now for the test...

For those looking to compare the Bolt EV with the Model 3, the Bolt EV may have 60% (!!) more aero drag than the Model 3. This might translate into 30% less range than the Model 3 at 75mph. That could be a difference of 50 miles.
Bolt EV: 125 mi
Model 3: 175 mi

This discrepancy highlights one likely reason why GM isn't investing in a long range, fast charging infrastructure. Their BEV is not optimized for long range travel. Will the Bolt EV be an effective suburban runabout, absolutely; but expecting the Bolt EV to be a time-efficient cross country cruiser is misplaced.

Sooo, R&T just took one & set the cruise @ 75MPH with the AC at 72 degrees & went 190 miles. What do you figure accounts for the massive over performance in the real world compared to the estimate?

 

[eops]

Not a good look for GM, sort of giving Tesla more room to grow and now Toyota wants in on the action so it might turn out to be more of a game where Toyota and Tesla are higher up in the EV world with GM falling behind.

 

[DucRider]

Not a good look for GM, sort of giving Tesla more room to grow and now Toyota wants in on the action so it might turn out to be more of a game where Toyota and Tesla are higher up in the EV world with GM falling behind.

huh what?
In real world testing, the Bolt outperforms predictions (based on lab tests and specs) and it reflects badly on GM?

 

[Zoomit]

Sooo, R&T just took one & set the cruise @ 75MPH with the AC at 72 degrees & went 190 miles. What do you figure accounts for the massive over performance in the real world compared to the estimate?

The Bolt EV has 20% more range than the range I was using as a baseline in August. In October the 238 mile EPA range was released, which is ~20% more than 200 miles. Increasing my 125 mi estimate by 20% is 150 miles. 150 miles is still a good planning number for high-speed (75+ mph) highway travel. You'll never plan to go to empty and extra margin is critical; for example, if you assume the Bolt has a 190-mi range at 75 mph, an unexpected and unnoticed 10 mph headwind decreases range to 155 miles.

 

[devbolt]

Sooo, R&T just took one & set the cruise @ 75MPH with the AC at 72 degrees & went 190 miles. What do you figure accounts for the massive over performance in the real world compared to the estimate?

Actually, it was Car and Driver who did the test:

We’ve already verified that the Bolt will actually cover 238 miles during a leisurely jaunt up the California coast that left us with an indicated 34 miles of remaining range. However, the quadratic effects of aerodynamic drag mean that the faster you drive, the faster the battery drains. So in our most recent rendezvous with the Bolt, we performed a real-world range test that mimics a long highway road trip. With the cruise control set to 75 mph and the climate system set to 72 degrees, we drove the battery to exhaustion in 190 miles.

http://www.caranddriver.com/reviews/2017-chevrolet-bolt-ev-test-review