Aerocivic - how to drop your Cd from 0.31 to 0.17

[Tercelerat0r]

@basjoos major major props on really going all out with aeromodding your CX...is it actually a Civic CX or a CRX? I have a friend who has a Red CRX that looks alot like your CX, and even stock he gets like 40mpg.

[basjoos]

Originally Posted by Tercelerat0r

@basjoos major major props on really going all out with aeromodding your CX...is it actually a Civic CX or a CRX? I have a friend who has a Red CRX that looks alot like your CX, and even stock he gets like 40mpg.

Its a 92 Honda Civic CX. When stock, it gave me upper 40's mpg in the summer and lower 40's in the winter.

[basjoos]

As requested, here are pics of my car as it currently looks.

[basjoos]

Wayne Gerdes got a chance to drive my car while at the mpg meeting at Columbia. According to the SuperMID he got 93.8mpg while driving my car on about a 8 mile stretch of interstate at a range of speeds between 65mph and 45mph. He said it coasted better than any car he has ever driven and would beat anything except an Insight in highway driving at the speeds he was driving at (and that it would beat an Insight at higher speeds where it couldn't remain in lean burn).

I averaged 65mpg driving both to and from the meeting at the speed limit and averaged 62mpg on the stretch heading home on I-26 at 70mph in heavy traffic where I couldn't do much DWL.

[Cd]

93.8 MPG ! That's great !
Now the questions that I think all of us are wondering :

1 ) How much of this was coasting with the engine off / in neutral
2 ) Was any of this going downhill ?
3 ) Did you reset the SuperMID mid trip, or at the beginning of the trip ?
4 ) Was the engine aready warmed up, or did you have a cold start ?
5 ) The 93.8 MPG was his average MPG ?

(93.8 MPG is fantastic, and I was just wondering how much of this amount could be attributed to the lower Cd of the car versus driving style )

Major props on having the balls to really go overboard and create something that YOU like, and not worry about what others think of it !

[basjoos]

About a third of it was coasting with the engine off. It was a very gently rolling terrain with the downhills so gradual that no other car would have been able to maintain speed on them (Wayne mentioned that even a HCH or Prius wouldn't have been able to maintain speed on them without having to use the engine). From a topo map, there was a net 20 foot drop from start to finish on that 8 mile segment. There was a light front quartering headwind. I reset the MID at the start of the return leg after Wayne had a chance to get a feel for what my car could do. The engine was warm as I had recently gotten back from giving someone a ride. That 93.8mpg was the average over that segment, which included accelerating the on-ramp onto the interstate, cruising on the interstate, exiting the interstate and catching 2 red lights on the way to the dealership. Wayne mentioned the total lack of wind noise in my car and the sturdiness (lack of popping, grinding, and other noises from the mods) of the mods. He also mentioned that he could probably have gotten 120mpg if my car had a lean burn engine and that it could probably remain in lean burn to over 80mph. One of the reasons that Wayne ridge rides is to catch the attention of overtaking traffic that something is different (driving slowly) about his car. He found that with my car he was catching the attention of overtaking traffic without having the ridge ride.

The good mileage was a combination of low Cd and driving technique. The low Cd enabled Wayne to FAS on very gentle downhills that would have been impossible to FAS at highway speeds with any other car, so he could spend more coasting with the engine off than he could if he had been driving the HCH.

[Christ]

I'm not sure, and I'm too lazy to look back... but is the new boat tail smoother than the old one?

It looks better somehow than the old one did.

[basjoos]

It has a smoother transition where it attaches to the OEM hatch hinge on top, but otherwise is very similar to the old boattail except for the additional taillighting.

[MetroMPG]

Thanks for the update & pics, Mike.

The additional lights are a wise addition, and will be part of my car's evolution when the time comes add tapered bodywork that will require the obscured OEM tail lights to be supplemented with extra lighting.

[Christ]

Something seems different, I guess.

Nice job fixing/replacing it though.