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

I did some A-B-A testing today on the U.F.O. (2000 Honda Insight 5-speed).

http://ecomodder.com/imgs/insight-front-3-4-500px.jpg

With five relatively simple aerodynamic mods/deletions (not shown in the above pic) ...

• partial grille block
• deleted passenger side mirror
• flat-folded driver's outside mirror (from a Suzuki Swift)
• deleted wiper arms: passenger side & hatchback
• deleted stock front licence plate bracket (flush mounted plate)

(List is in order of estimated effect of each mod on drag reduction, from most to least effective.)

I measured a 14% gain in MPG at 80 km/h / 50 mph: 94.6 mpg (US) vs. 82.9 mpg.

I tested the mods collectively: ie. the "group" of mods was in place for the "A" runs; reverted all mods to stock setup for the "B" runs.

Note: testing was done with the car's hybrid functions completely disabled. (Since I got the car, I've been driving it with IMA switched OFF to protect the near-dead high voltage battery pack from further damage.)

All of which means: those steady state MPG numbers simply show the advantages of a small, efficient lean burn engine + tall gearing + good aerodynamics! No electric assist was involved (which possibly would have made the numbers slightly better).

It's exciting to see how "expanding" the car's lean burn "envelope" can pay big dividends! (Moreso than these same mods done to a non-lean burn vehicle, I mean.)

I will report back with the raw data & some photos later.

Weather, Sat., Sept. 24, 2011

Overcast / damp roads (not wet - no road spray; from light mist earlier in AM)

Metric units
Time ... C ... Humidity ... Dew point ... Wind kph ... Press kPa
14:00 ... 19 ... 89 ... 17 ... SW 7 ... 101.7
13:00 ... 19 ... 94 ... 18 ... SSW 5 ... 101.7

Imperial units
Time ... F ... Humidity ... Dew point ... Wind mph ... Press in.
14:00 ... 66 ... 89 ... 63 ... SW 4 ... 30.02
13:00 ... 66 ... 94 ... 64 ... SSW 3 ... 30.03

A: 2-wiper delete (1 front, rear); grille block; passenger mirror delete, driver's folded; licence plate bracket delete
B: stock config

Speed: 80kph / ~1728 rpm

A ... w ... 86.4 ... 89.0 ... 90.9 ... 91.4 ... 91.4
A ... e ... 97.0 ... 99.1 ... 99.1 ... 101.0 ... 102.2
A Average (W & E): 94.8 MPG

B ... w ... 78.2 ... 71.7 ... 75.9 ... 74.0
B ... e ... 90.9 ... 92.1 ... 91.1 ... 89.5
B Average (W & E): 82.9 MPG

A ... w ... 90.2 ... 90.4 ... 89.3
A ... e ... 98.7 ... 98.7 ... 99.1
A Average (W & E): 94.4 MPG
Average all "A" runs: 94.6 MPG

Standard deviation of all A runs (averaged bi-directional pairs): 1.5 MPG
Standard deviation of all B runs (averaged bi-directional pairs): 1.3 MPG

Difference of A over B: 11.7 MPG / 14 %

MPG readings taken by resetting OEM segment fuel economy calculator when passing a chosen signpost after getting the vehicle up to speed & stabilized. Final reading taken at a second signpost at the end of the route. (One update of the OEM display.)

Route: 1.6 km straight and flat section of smooth road, with no other vehicles ahead in my lane; occasional vehicles in opposite direction.

No cruise control. Speed was controlled by watching RPM instead of the digital speedometer readout, because the speedo gives no indication of rising/falling speed until the next higher/lower digit is shown. RPM has higher resolution.

That's incredible !
If it wasn't you doing the testing, I would have my doubts, but you are always meticulous about your testing.
Did I read those numbers right ?? Over 10 MPG ?

Yup, over 10 mpg.

It was such a big change because the mods permitted the car to operate in lean burn 100% of the time at 80 km/h, where without them it felt like it was on the edge, moving in & out of lean burn at the slightest change in throttle position to maintain that speed.

In other words, the % change might have been less impressive if I'd tested at 70 km/h or at 115 km/h (either fully in, or fully out of lean burn for both A and B runs).

I didn't plan it that way, but it was interesting to discover. I tested at that speed because it's the highest posted limit on the secondary roads I usually travel.

1. What's that car got for an undertray "as is?"

2. Batteries: What's the cost to replace the stock batteries? Would something as simple as Costco marine deep cycle batteries work as a suitable replacement?

3. If you just took the batteries out and ran without them, approx. how much weight savings? Fuel savings?

4. What tires, tire pressure?

One of the first things I plan to do if I ever buy one of these cars is to remove the mirrors and replace them with something smaller.
How bad of a blind spot do these cars have without the passenger side mirror ?
I remember sitting in the car at the dealer when these cars were new and being turned off by the blind spots the car had compared to my Civic hatch, but can't recall just how bad that it was.
I have seen others remark about the blind spots on this car and I notice despite going all out on the aerodynamics of his Insight, 3Wheeler chose to leave the stock mirrors on.
How bad were the blind spots in your case ?

This matches well with Basjoos' findings.
His mods allowed lean-burn at higher speeds due to less drag.
We need more Insights on the road........alas.

Pictures of the grill ?

"After" pics? :)

Great testing Darin. Gotta love lean burn!


1) The insight has some undertrays, its not nearly a solid/flat surface though.

2) He'll be rebalancing and replacing parts of the pack if necessary. There is a pretty good thread by RobertSmalls that tell you how to do it. You can not use deep cycle lead acid batteries.

3) The entire pack only weighs 65 lbs. Fuel savings from removing it would be nothing.

Interesting test results on your Insight.
 

It would be interesting to see what you could get out of your Insight with a boattail on it like you built for your Metro.

Here is a little more insight on the Insight. (you guys have probably seen this link already, this is for those who may not have yet.)

InsightCentral.net - Encyclopedia - Honda Insight Aerodynamics

Bondo

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.

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.

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.

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)

http://ecomodder.com/forum/attachmen...1&d=1317002272

http://ecomodder.com/forum/attachmen...1&d=1317002272

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.

http://ecomodder.com/forum/attachmen...1&d=1317002272

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.

http://ecomodder.com/forum/attachmen...1&d=1317002272

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 )

http://www.metrompg.com/posts/photos...ded-detail.jpg

Testing info/data added to post#2.

---

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.

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 ?

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).


http://www.metrompg.com/posts/photos...t-z-b4-aft.gif


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.

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.

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.

Video mirrors would be nice! :-)

Yeah - I've seen them on a couple of Insights.

What kind of results would you have got with the non manual version of the Insight ?

Also, I might suggest looking at picking up a mirror from a '92-95 Civic .
Since its Honda, it might fit better.
Also, the mirror folds back easily all the way back and pops back out with one hand.
Even the shape seems meant for this .

Here is the mirror folded back - actually I'm holding it because I flipped it back so many times i broke the spring mechanism.
The blocky piece on the mirror itself is an aftermarket fisheye mirror . the stock mirrors don't have this appendage.
If you look at the shape from the side and especially from above, it almost seems designed to be folded back for good aero.
Perhaps a trip strip could be added along the back to make it even better ?

I can imagine a servo that would be triggered from within the car at the flip of a switch. ( to move the mirror flush. )

One of my friend had electric folding mirrors in his RHD mitsubishi galant vr4.

You just had to press a button and both mirrors would fold. Never seen that on any other car

Just found a video of these on youtube

http://www.youtube.com/watch?v=5ha1lC8VI2U

The Lexus LS-430 also had mechanical folding mirrors.

Nice results. For the adjustable grill block here is my execution:.

http://tuneko.com/gallery_d754816d47...05ec726dea.jpg
Custom flap and the adjustment will come from front light height adjustment motor. You can find 3 wire motor so its very easy to connect.

Quite a few cars have them here, I was disappointed that the Prius didn't when it arrived. My dad's poverty spec Skoda has them after all.

And my Pug307 also has electrical folding mirrors. The only problem is that pushing the fold/unfold button operates both at the same time. I've thought about a workaround, but it appears that I can't adjust them unless both are unfolded:(

Do you adjust it manually or does it adjust with temp, do you have a link with details ?

At the moment it does not even have the adjustment but I will use light height motor and its adjustment switch. adjustment will be manual so I have to monitor the water temps... Valve is installed to just 10mm bolt which goes through the subwoofer box 100mm air port. Just grind half off from the bolt and screw round plate in it.

Wow -- all your cooling is through a ~4" round port? Is the rest of the cooling tract smooth and ducted? Where is the exhaust flow going?

The Lupo's 1.2 TDI is so effiecient that it barely stays at operating temperature. During the winter months the car uses electric heating elements for cabin heat. (Saw a link somewhere, I'll post if I find it.)

EDIT (02-10-2011): Here's the link: First Drive: Volkswagen Lupo 3L TDI

yes that is more than enough cooling for my engine. Not yet its not ported/tunneled through the hood but it will be. Exhaust come off behind the left front tire... We can continue this in my Lupo thread http://ecomodder.com/forum/showthrea...-2l-18235.html

I have yet to see any mirror that I truly like. I think that everything is going to leave some turbulence along the sides of the car. It would be interesting to try to find a way to design something at mid window which would fold flat against the window glass. I say mid window because small mirrors are more effective if they are close to the eyes. All this just might be impossible dream, but what is brainstorming good for otherwise ;-)

Some cars are fine-tuned to have the external mirror inside a pocket of turbulence, or at least partially inside. Folding it allows the outer edge to hide inside that pocket.
Tuft testing would show which car/mirror combo would benefit from folding.

To folded mirror I would add small convex mirror to the tip that would work when the mirror is folded to be able still to see ;).

eBay has reasonably well streamlined motorcycle mirrors which fold, cheap.

Hmmm, I have some on order from the bay of flea, I may try that...

This is the plan!

I used a small piece of aluminum cookie sheet to make a bracket at the correct angle and cemented it to the mirror glass near the hinge so it gives me a wide view when the mirror is folded. I stuck it on the glass with clear silicone sealant so I can hopefully remove it if the need arises.