evnow said:
fotajoye said:
GRA's...
I should also note that long range and low aero are opposing demands. For example, in the current Leaf they can take out some battery and lower the rear seats and thus the roofline to get better aero. When we are talking about compact cars, volume of the battery matters as much as the cost.
Nissan clouds the issue even more by quoting Japanese range cycles and kilometers without disclosure...which to the ignorant sounds great until you buy one and take it out into the real world.
One thing you can safely bet on, the 200 mile range quoted by Nissan is optimistic.
Nissan doesn't use kilometers and NEDC or the Japanese cycle when talking to US press (in US). I don't expect them to use EPA numbers when talking in Japan.
This is the reason "double range" is a good indicator. You can use whatever cycle or scenario you want to get approximate range of next gen Leaf, if you know current Leaf's range.
I guess it's OK to go into this since you are the moderator:
Here is a list of just some of the things an engineer can change to improve an EV's aerodynamics:
Round the edges of the front end
Tune the grille and fascia openings
Tune the wheel openings
Place small spoilers in front of the tires to reduce turbulence
Tune the size and shape of the outside mirrors and their attachment arms
Install cameras instead of side view mirrors
Reshape the water channel on the A-pillars
Adjust the front fascia and air dam to reduce drag under the vehicle
Add side skirts
Tune the deck height, length and edge radius
Install a rear spoiler
Adjust the angle of the rear window
Use a diffuser to tune air coming off the underside
Install "belly pans," underbody panels that cover components and smooth airflow
Install air dams that drop lower at higher speeds
Install rear spoilers that pop up to reduce lift at higher speeds
Lower the vehicle at speed
Like airplanes, pinching in the roof line and sides to help maintain a gradual decrease in the surface as it goes to the back of the car will assist in keeping the boundary layer close to the surface and from burbling off disruptively. And, If you look carefully, you will see that is done on the Leaf to a small extent already. In fact an ideal aerodynamic shape for a car is a tear drop with a Cd of about .05 and one of the worse is a flat panel fully into the air flow with a Cd of about 1.25. Unfortunately, cars must be practical devices so there are compromises and that's why the great attempts to reduce the aerodynamic drag. As I have stated before the Cd of the Tesla S is about .24 and a Leaf is .28. The formula for aerodynamic drag is AD=F*Cd*D*V squared; where F is the car's frontal area; Cd is the car's drag coefficient as defined by the car maker; D is the air density; and V is the car's velocity squared. Since the velocity is a square function, it has a great effect on drag, If you double a car's speed, for example; from 35 mph to 70 mph, the drag will increase four times. While the speed has a great effect, the 14% difference between a Leaf and a Tesla's Cd(.04) would make little difference.
Here is a nice explanation of aero for gassers:
http://www.edmunds.com/fuel-economy/improving-aerodynamics-to-boost-fuel-economy.html" onclick="window.open(this.href);return false;
At this point of the Leaf's development; removing some of the battery cells to lower the seat only makes sense if you don't want a full range battery. I'll take the range.
And lastly, Nissan did quote figures based on NEDC in kM/hr to everyone including the press when the Leaf was introduced; I take your word they don't do this to press people now. It will be interesting to see if there is a significant difference between what they announce and what one gets in range with the next generation Leaf. An honest 200 mile range figure would be most welcomed.