2000 Honda Insight: 14% better MPG @ 80 km/h (50 mph), with 5 simple aero mods (ABA)

[MetroMPG]

Brett - you better believe a removable boat tail is in this car's future.

Also an improved coroplast undertray... and a few other aero things.

Of course the question is "when?" (Too many projects!! Thus the car's nickname: U.F.O. = another Un-Finished Object.)

Will post a few pics of the mods tested, later today.

[Big Dave]

I always wished I could find a way to stuff my porky bod into an Insight. I'd need a "Gurney bubble" the size of a P-51 canopy.

But the car is an engineering jewel.

[jime57]

I've had mine for a couple of years now. It has been unmodified except for a couple of things. I used a full lower grill block in cool/cold months and I use a block heater as often as I can, especially in the VA winters - makes a huge difference on relatively short trips.

I have gotten some great driving advice from Sean(aka Right Lane Cruiser) over on CleanMPG. I think driving skills make a huge difference with this car, and the skills are definitely different than any other car. Sean has emphasized low engine speed(i.e. short shifts), staying out of assist as much as possible(assist being an inefficient process) and spending as much time as possible in lean burn, as you identified.

I went to hybrid fest in Madison a couple of months ago and got 103+ MPG from Madison to Wheeling, where the eastern mountains set in. No grill block and no mods - just driving skills taught by Sean. I ran very high tire pressures, to which the car is very responsive. I will admit that my average speed was probably less than than 50mph. I have found that an occasional 3 blips of the flashers when a truck is catching up pretty much takes care of the faster traffic.

I found your test results very interesting and want to do some of these things myself. As I said the grill block has helped me a lot also. I'm retired and should have the time to make modes, but I seem to have so many irons in the fire I just can't get around to doing much, so thanks for the results.

For those who ask about visibility with mirror removal, I must say that I found from experimentation that it is terrible. The car is normally rather poor on that score and taking mirrors off is something I haven't been able to sort out so far. The folding Metro mirror is interesting and might be the key for me too.

[MetroMPG]

I agree, the car's rear & 3/4 rear visibility isn't very good. That' s the price you pay for lots of plan & profile taper!

While I removed the passenger mirror entirely for the test, I will be making a custom, smaller replacement. I don't need the passenger side mirror for the driving I do, but I sometimes back into extremely tight parking, and need to be able to see beside the car.

FYI, and someone else asked, the tires were at 55 psi for the runs.

Some photos of the mods that aren't self-explanatory...

Grille block - full upper & partial lower ... (tape & thin plastic sheet)





This is fine for low-to mid-20's (C) temperatures, including city driving (engine is off when coasting/stopped).

Plan is to make a nicer looking permanent version of these pieces.

The side mirror is from a 1990 Suzuki Swift. (This one.) The stock Insight mirrors fold, but not really very much. The Swift mirror is not a perfect fit - its mounting base doesn't fill the triangle of space the OEM one occupied. Currently there's duct tape sealing the gaps - I need to work on it.



When folded, the Swift mirror presents roughly ~40% of its usual frontal area. (Can't speak for the change in Cd). I only fold it when driving on 2-lane highways.



I made a filler "plug" to deal with the mess created at the exposed hinge when the mirror is folded. It's very easy to pop this plug in & out with one hand. I borrowed this part from the Firefly. (Wrote about it here: Reflections on side mirrors: testing drag vs. MPG - MetroMPG.com )

[MetroMPG]

Testing info/data added to post#2.

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What prompted me to do this test was a pair of recent highways trips (the same trip, repeated on 2 weekends) to visit friends at a cottage.

It's 293 km (182 mi.) round trip, on secondary roads with a max posted limit of 80 km/h (50 mph). It includes passing through a number of small towns and one small city.

The first time I did the trip before the mods were all in place. My goal was simply to drive with load to keep the car in lean burn at ~100 mpg on the instant display, or higher when at the posted speed limit. I got something like 89 mpg US for the first round trip.

The second trip, in nearly identical weather conditions with all the mods in place, I used the same techniques (~100 mpg target), but I managed to do the trip in 20 minutes less! How? Because the car spent more time going faster on the highway while still maintaining at least 100 mpg indicated. And there was quite a bit more traffic (stop & go) in the city portion of the second trip.

And I ended up with 94 mpg US for the second round trip.

[Arragonis]

How does this compare in terms of speed vs MPG with the Blackfly ?

And can you fold the mirrors and insert the blanking piece whilst moving or do you need to stop when you switch from 2 lane roads to wider ones, if you do swap that is ?

[MetroMPG]

Folding the mirror and dropping the plug in place is quick & easy - I can do it on the go. The blank has a "pin" that drops into a hole drilled in the exposed hinge. Lower window, fold mirror, drop in plug. No muss, no fuss.

This is the only test I've done with the Insight so far, so it's a single speed vs. mpg data point, but the Firefly is good for ~65 mpg (US) at 80 km/h (50 mph).





Lean burn 1.0L Honda, lightly modified: ~95 mpg (US) @ 80 km/h (50 mph)

Non-lean burn 1.0L Suzuki, moderately modified: ~65 mpg (US) @ 80 km/h (50 mph)

Lean burn wins, hands down.

[3-Wheeler]

Originally Posted by MetroMPG

Folding the mirror and dropping the plug in place is quick & easy - I can do it on the go.....

Hi Metro,

Hey, very nice write-up! My eyes were bugging when I started reading about your results.

I'll bet one could fashion a mirror shape/hinge that does not require the use of a plug in that particular spot. Would take a little "modelling" to work out the shape, but that would certainly make things easier.

Both of the those grill blocks look very effective, but I would want to make those into a "venetian blind" affair that allows either automatic operation or manual from inside the car. Someday....

Thanks again, Jim.

[MetroMPG]

Hi Jim -

You're right - I've seen stock mirrors on different cars which fold flat (much better than the OEM Insight ones), and don't have that messy "open" hinge like the one I took from the Swift GT. Just working with available materials.

And I agree - a variable grille block would be best. That would also allow a 100% block until the engine is up to operating temperature. Happyface!

Some day is right.

[NeilBlanchard]

Video mirrors would be nice! :-)