9th Gen Civic Forum banner

9th gen Civic drag coefficient

28K views 17 replies 10 participants last post by  Roadcourse 
#1 · (Edited)
Hi I was wondering what the 9th gen Civic drag coefficient was, and what exactly was done to the outside body to make it more aerodynamic. I read about the underbody panels, the hood and mirrors, but I wanted to know what they did with the back (trunk area). It seems as if they raised the back end to make the trunk tilt upwards. I also read about the 2005 toyota camry and it said that it had a drag coefficient of 0.28. It said on some site that the Civic's drag has been reduced by 9% compared to the 8th gen. Is this car more aerodynamic than the 2005 toyota camry or is it equal to it?
 
#2 · (Edited)
Can't tell you. It's probably in the neighborhood of 0.26-0.30 where most cars are. Drag reduction is achieved through targeting design features that keep the airflow attached to the car, minimizing vortex shedding. That can be achieved in a few ways:

1) Any reduction of turbulence in the flow. Specifically sited in the 9th gen design is smoothing of the underbody to prevent unsteady flow.

2) The continuously sloping roof on the back of the coupe and decklid placement can help reduce the drag. The abrupt change at the back of the car will typically create a swirl (best seen in the idea of drafting on semis, bike races, etc - the vehicle in the front creates a "hole" in the airflow that is low pressure). That will change the flow patterns behind the car, effecting the flow in the front and by tapering the back of the car, you can minimize/maximize some of that effect to help improve the drag coefficient.

3) The HF is lowered a bit to help in the aerodynamics. You want to minimize the total effective frontal area of the car.

4) The body lines along the hood and the sides of the car can be designed to minimize the flow separation. The angles which the seams point along the side of the car will act like tracks for the air to flow along.
 
#3 ·
0.31 Honda Civic (Sedan) 2006-2011
0.28 Honda Civic (Coupe) 2006-2011
0.27 Honda Civic (Hybrid) 2006-2011

Gotta keep looking for the 2012 stuff...
 
#4 ·
If the 9% reduction that skaarj said is true, and the reduction holds true through all three mentioned body styles, then the sedan should be 0.28, the coupe should be 0.25, and the hybrid would be 0.25 (rounding up) to bring it in line with your supposition that the drag coefficient should be between 0.26-0.30. Of course, those are not the Honda numbers (just me multiplying each coefficient by 0.91), so they could be slightly different. Therefore, the drag of the Civic sedan would be the same for the Camry sedan.
 
#7 ·
I've noticed that the rear bumper facia was changed for the 9 gen. It looks like it sweeps up more at the ends and sticks out a wee bit more across the back. This could also help with air leaving the car.
 
#8 ·
Who said 9% lower!?!? Most websites state 3.4% lower than 8th gen, for example, here on msn autos:


"Honda never cites actual drag coefficient figures, but claims the new Civic has best-in-class aerodynamics, with a Cd 3.4 per cent lower than the 2011 model - and the Hybrid is even slicker still." (link here)


Road and track says there's an extra 4.4% cd lowering for the hf, but they don't say compared to what (compared to the normal 2012 civic models, or compared to last gen civic non-hf models?):


"For the hypermiling frugalista, there’s the [2012] HF model whose coefficient of drag is lowered by 4.4 percent through flush wheels, aero underbody/gas tank covers and a rear lip spoiler." (link here)
 
#9 ·
Who said 9% lower!?!? Most websites state 3.4% lower than 8th gen, for example, here on msn autos:


"Honda never cites actual drag coefficient figures, but claims the new Civic has best-in-class aerodynamics, with a Cd 3.4 per cent lower than the 2011 model - and the Hybrid is even slicker still." (link here)


Road and track says there's an extra 4.4% cd lowering for the hf, but they don't say compared to what (compared to the normal 2012 civic models, or compared to last gen civic non-hf models?):



"For the hypermiling frugalista, there’s the [2012] HF model whose coefficient of drag is lowered by 4.4 percent through flush wheels, aero underbody/gas tank covers and a rear lip spoiler." (link here)


I think I it said 6% actually but maybe the site was wrong and I don't remember which site it was.
 
#11 · (Edited)
Aerodynamic 9th Gen..,

I figured the mileage rating of the EX I bought was partly due to the shape of the body, but it really showed up yesterday. We drove Black Betty all day in the rain. This morning, I went out in the garage and noticed the only dirty area on the car was on the rear end. The back of the trunk lid and the back of the rear bumper are the only places that show dirt accumulation. There's not even really anything behind the wheels. Apparently, the freebee splash guards the dealer installed work. Still lovin' this ride.
 
#13 ·
Yeah, I was trying to fix it, but you posted b4 I could delete the bad one. Please do it for me? Thanks,
 
#16 ·
Prolonged exposure to rain really shows you the stripes of the cars aerodynamics. It's really quite interesting how the air flows around the car. The engineers did their homework on these cars for sure.
 
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