Would I be correct in assuming that most aftermarket body parts for Hondas have never been wind tunnel tested and that their effect on drag, down force, air intake or air extraction is pretty much a guess? Wind tunnel time especially, for a real car as opposed to a model, isn't exactly inexpensive.

 

doesn't matter. our cars arent very aero dynamic to start with, nor go that fast to really matter.

just get the pieces for aesthetics.

 

It does matter if you care about fuel economy. Aerodynamic drag is as large or a larger factor than mechanical drag at constant speeds as low as 35 - 40 mph in most cars. Aerodynamic drag increases with the square of velocity. If you are taking a road trip with a relatively constant speed of 65 - 70mph even small changes in frontal area or the overall drag coefficient are significant. The Fit may not have the slipperiest shape out there but compared to something like a VW Beetle it is actually quite aerodynamically efficient.

 

It's safe to say that adding just about anything increases Cd. What exactly are you asking?


In some cars/scenarios, one might make that trade-off for greater downforce at high-speeds. For others, the 'look' is worth sacrificing an MPG or two.

In the fit, any bolt-on bodywork is definitely for the latter.

 

I was trying to find out if any of the available aftermarket body parts were about anything other than show and if so, which ones. I suspect that something that further cleaned up the trailing edge flow or perhaps a full belly panel would actually decrease Cd. If there are exceptions that try the rule I'd like to know what they are.

 

Well the beatrush underpanel was said to have a small effect on that matter...
you can also look into the Kammback aero spoiler!
you could also put stupid tiny mirrors...
pie cutter honda wheels
That's pretty much what i think of right now!

 

hehe: Scientific Method meets Fuel Economy: Kammback


I suppose there are things you could do, but I wouldn't think any would get more than one or maybe 2 mpg? Even in that super extreme [ly sweet] escort mod above, he only net'd a 4mpg improvement.

Is it legal to remove the passenger-side mirror?

 

lol not "that" extreme:
DIY ‘Boat Tail’ Gives Little Car Big Fuel Economy | Autopia | Wired.com
Aerocivic - Honda Civic modifications for maximum gas mileage - aerocivic.com

honestly, i would never turm my fit in such an horror... but to each is own...

 

you will net more mpg by over pumping air into your tires and keeping constant cruise speed 2.5k-3K RPM range, i think. and remove the spare and everything inside not needed including rear seats, get in shape by trimming off excess fat, etc.

 

Weight has a significant effect if you are driving in conditions where you are frequently changing speeds but at relatively constant velocities such as driving on a relatively flat and uncongested section of interstate (North Dakota?) it is a minor factor. I have no idea what the fuel economy impact of over pumping tires would be although I suspect it isn't huge and the downside in ride and handling has to be unpleasant.

I loved the DIY aerocar links. Obviously these guys aren't afraid to be to be viewed as more than a little eccentric. The craftsmanship leaves a bit to be desired and I'm not convinced that whale tails are the best solution for real world driving and parking but big points for the wacky factor.

The VW L1 and XL1 prototypes/show cars demonstrate where very low weight and very low Cd can take us:
VW Redefines ‘Car’ With A 170-MPG Diesel Hybrid | Autopia | Wired.com
Volkswagen XL1 Concept - First Drive - Automobile Magazine

I think we have a reasonably good handle on the engineering and materials science needed to produce a very low weight, low drag vehicle although the tooling and productions costs are likely to be significant. The big hurdle is to create a significantly more efficient engine.