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

[mikep_95133]

On my way to my gf's place, at 50-55 mph I got 103mpg several times, 84 miles round trip. This was from San Jose to SSF on highway 101. I think the hybrid system helps.

I've had my 02 Insight for about 20 months. In the summer I have run a cardboard grille block on only the lower grille using bailing wire to hold it in place. The previous owner took off the rear wiper and plugged the hole with a rubber stopper. The car also has a spdt switch for activating the clutch switch or the brake switch and the front plate frame remove, all from the previous owner. It also has a ScanGageII from the previous owner. LT fuel economy when he had the car was at 70mpg. It's now at 61.1mpg. 225k miles. Tires are at about 35% tread and full pressure. Mobile1 0w-20 in the engine. White cap Honda MT fluid in the trans. Both need changing. I have only cleaned out the egr plate and had the injectors cleaned and tested out of the car. I only hyper mile going to SSF, which is almost never as she stays down here most of the time now. When the weather gets hot, the Scan Gage shows 206F too often. So I take out the grille cover in the summer. I am due to put it back in soon.

[jime57]

Thanks Mike. I got essentially the same mileage on a very long run from Madison to Wheeling a few months back. That was before I had to buy new tires. The tires have lost me 2-4 MPG for now. I'm hoping for an early breakin.

The Insight design is a very sudtle tradeoff. Of course the regeneration helps recover lost energy on braking and decelleration, but that effect is very minimal on long runs like you spoke of. I'm familiar with the route you quote and it is almost totally flat. Therefore assist should very seldom activate. In other words, you are actually using the hybrid features very little. In addition, you are likely in lean burn most of the time, at those speeds.

As I said, IMO the manner in which the hybrid helps is subtle. It allows Honda to use a very small displacement engine, and have the needed reserve power on tap with assist. Most experienced folks think that actively using assist/regen damages fuel economy. Of course conventional wisdom can sometimes be wrong ;-)

[3-Wheeler]

Originally Posted by jimepting

...Do you think that a better boat tail might be designed by reducing the angle just where the hatch ends and the tail begins?

Yes.

I still have a hunch that the downward sloping angle of my tail is too steep, and does not match the existing angle of the Insight hatchback well enough.

Changing it would not be easy since the tail is almost finished, but the idea is still in the back of my mind.

Tuft testing would certainly help.

I just thought of a mounting location for the "remote" camera that Metro used. The license plate mounts!

Will keep that in mind.

Jim.

[3-Wheeler]

Originally Posted by COcyclist

Me too. Although if you look at threewheeler's fuel log, it has been really climbing since the tail was added. He is obviously doing something right. He mentions some electronic mumbo-jumbo that a diesel owner like me, doesn't understand and that could have something to do with it too. I have to think the air really likes the shape though.

Hi,

The main reason for the large increase in mileage has less to do with the tail at my slow driving speed (40 mph) and more to do with the HV battery control board (MIMA-CL) and engine off coasting (FAS). Highway driving is a whole other subject!

I use up the HV battery to/from work each day and trickle charge at night. The gas savings are about 3 times more than the electric cost to charge it back up.

But by far, the largest gas savings is simple, low tech, coasting with the engine off.

From what I can tell by doing this for 1/4 year, is that anyone getting over 120mpg with an Insight is doing major coasting. I saw one 33 mile trip home this year at 136mpg by doing just that and a hot 95F summer day.

Jim.

[mikep_95133]

Hi Jim,

I'm glad to hear FAS is showing such an improvement. It's my favorite mod. I've followed the development of the hardware since it started. I just have too many irons in the fire to mod my Insight.

I noticed that my camber is a bit positive these days. I think that's the 225k miles. I need to look into what parts are wearing.

Mike

[3-Wheeler]

Originally Posted by jimepting

.....Most experienced folks think that actively using assist/regen damages fuel economy. Of course conventional wisdom can sometimes be wrong ;-)

I would say, it depends:

If your taking a long trip, then use assist/regen in a way that you have extra when you need it.

On the other hand, over a short trip, like my trip to work, I get a very steady 10% increase in mileage by using up the battery to/from work. And the battery loves the exercise! It took about 20 trickle cycles before the battery started to perk-up after being lazy for so many years.

One more note: the battery definitely likes the temps to be cooler than 70F. I would venture to say that the amp-hours of the battery has gone up by 30% since it got cooler rather than the 90F-100F temps this summer.

Jim.