Comparison of Aerodynamics

[tonymil]

I just came across this article that compares the aerodynamics of the Tesla model S, Nissan Leaf, Toyota Prius, Chevy Volt, Mercedes CLA 250 and a 2001 Honda Insight for Hybrid.

http://www.greencarreports.com/news...odel-s-electric-car-wins-the-wind-tunnel-wars

The Tesla did impressively well, but this quote really surprised me, especially considering the Tesla is 1400 pounds heavier:

The numbers get even more interesting: Did you know, for example, that a Model S requires just 14 horsepower to maintain 70 mph, 4 hp less than a Leaf?

 

[skyemoor]

Rolling resistance wasn't addressed, so weight won't make a difference in aerodynamics. The real world is different, though.

I noticed an old Insight was tested, though if it is like my 2000 Insight, the undercarriage panels are either missing or 'air grabbers'.

I just came across this article that compares the aerodynamics of the Tesla model S, Nissan Leaf, Toyota Prius, Chevy Volt, Mercedes CLA 250 and a 2001 Honda Insight for Hybrid.

http://www.greencarreports.com/news...odel-s-electric-car-wins-the-wind-tunnel-wars

The Tesla did impressively well, but this quote really surprised me, especially considering the Tesla is 1400 pounds heavier:

The numbers get even more interesting: Did you know, for example, that a Model S requires just 14 horsepower to maintain 70 mph, 4 hp less than a Leaf?

 

[tonymil]

Rolling resistance wasn't addressed, so weight won't make a difference in aerodynamics. The real world is different, though.

The comparison of horespower to maintain 70 mph would not have come from the wind tunnel test. I think it was thrown in to show "real world" effect of aerodynamics.

 

[skyemoor]

All I was trying to say is rolling resistance wasn't covered, so weight wouldn't matter in a calculation to estimate horsepower requirements to overcome wind resistance. So we are on the same page.

Here's a nice calculator on this subject;

http://ecomodder.com/forum/tool-aero-rolling-resistance.php

Rolling resistance wasn't addressed, so weight won't make a difference in aerodynamics. The real world is different, though.

The comparison of horespower to maintain 70 mph would not have come from the wind tunnel test. I think it was thrown in to show "real world" effect of aerodynamics.

 

[NeilBlanchard]

The most important factor is the efficiency of the drivetrain. Then aerodynamic drag, Then weight, and then all other friction.

Aerodynamics swamp all other drag at ~30MPH, and weight doesn't enter into it when driving at a constant speed.

Case in point is the Edison2 VLC - the version that won the X-Prize was ~840 pounds and a Cd of 0.164. It got ~102MPGe.

They then made an electric version, that raised the weight to ~1,140 pounds (an increase of almost 36%) and it got ~245MPGe.

Another example is a Honda 125cc motorcycle - stock weight is 231 pounds and MPG is ~90MPG, but with 80 pounds of aerodynamic shell and taller gearing - it gets 214MPG.

http://ecomodder.com/blog/diy-aero-fairings-honda-125cc-motorcycle-214-mpg/