100% improvement in mpg (...from '04 Aveo automatic to '00 Insight 5-spd)

[syncro_user]

Was the dealership seriously called Cheatham and Cheatham? I suppose they have to try extra hard to keep the customer satisfied with a name like that. Nice car.

[slowbro]

Yeah that's what a friend told me, but the owner and his son run the place, and their last name is Cheatham. Kind of unfortunate, huh?

[MetroMPG]

Like the Click & Clack (Car Talk guys) law firm: Dewey Cheatham & Howe!

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As for lean burn (LB), there is a custom x-Gauge you can set up if you have a ScanGauge which will show it.

Your butt & right foot may also tell you: in my car there is a subtle but distinct change in throttle response and a noticeable but very slight reduction in power when the engine transitions to LB. (If I hold constant throttle when at a steady cruising speed, the car will slowly begin to lose speed after the LB transition - so I have to give it ever slightly more pedal to hold my speed.)

The "instant" MPG portion of your OEM fuel consumption display (the bar graph) also shows you when you're in lean burn - it jumps up 25 mpg or more at cruise when the transition happens.

Good to hear you've got the right tires on the car.

Also, posted this today FYI: http://ecomodder.com/forum/showthrea...nda-23230.html

[slowbro]

Metrompg,

Thanks for the tips. I feel I have a good grasp of when lean burn kicks in, I just want to see the instantaneous mpg jump on my scangauge like the oem trip computer shows. I'll have to check up on the x-gauge add on.

Next weekend, I am planning on visiting a friend in Michigan, and I would really like to make the round trip on one tank (about 846 miles round trip, must average 80 mpg). I'm not sure if my hypermiling skills are that good in this car yet though. Are there any tips I could borrow from a fellow Insight driver? I'm pretty good at maintaining lean burn, I just think I need to lighten the touch on the throttle slightly to get the instantaneous while in LB up. Holding 75 mpg instantaneous is easy enough on a flat road while maintaining 50-55 mph (I can usually go higher than 75 on the instant). I typically have a hard time finding how far I can back off the throttle while still maintaining speed. I had it down in the Aveo, but not the Insight yet. What kind of instant mpg should I target while travelling at, say 55 mph? I'm going to practice tomorrow a little bit, but I'll have to see. Is 80 mpg a reasonable goal?

[MetroMPG]

Originally Posted by slowbro

I just want to see the instantaneous mpg jump on my scangauge like the oem trip computer shows

Aha! Well, you won't see it on the ScanGauge, because it doesn't register lean burn operation. The SG calculates fuel consumption by monitoring air consumption, and it assumes a stoichiometric (14.7:1) air:fuel ratio in its fuel use calculations. So when the Insight's engine transitions to lean burn at a constant load, the air consumption doesn't really change, so the SG won't report the jump in MPG. You have to rely on the Insight's factory gauges for MPG.

I'm pretty good at maintaining lean burn... What kind of instant mpg should I target while travelling at, say 55 mph? ... Is 80 mpg a reasonable goal?

The key to good cruising fuel consumption is monitoring/maintaining lean burn (driving with load / target MPG driving). So if you're good at that, you can achieve whatever MPG you want by adjusting load (speed, usually).

When I target 100 MPG minimum on the instant display while cruising, I usually end up with 85-95 MPG for the trip, after factoring in lower MPG on inclines, unexpected stuff, town driving at either end, etc. I'd say choose a route that gives you the most lattitude to adjust your speed as needed without disrupting traffic.

Also, since 55 mph is getting close to the lean burn limits of the car, have you done any mods that will help? Pump up the tires, do a few aero mods: see http://ecomodder.com/forum/showthrea...-km-18930.html

[slowbro]

I'm going to inflate the tires to 50 psi. They're at 40 now. Do you think 50 mph would make it easier to achieve my goal? I'm looking at various routes and I want to at least have a 4-lane highway to permit passing.

[MetroMPG]

50 MPH - definitely easier.

EDIT: in the mods thread I linked to, you'll see that with the Insight in "stock" form, my average MPG at 50 MPH on a flat road in ideal conditions was 82.9. After mods at the same speed: 94.6 (the partial grille block probably had the largest benefit of the 5).

[MetroMPG]

Congrats on beating your 80 mpg goal!

[slowbro]

Thanks metro,
And thank you so much for your advice. Holding lean burn is challenging

[MetroMPG]

Challenging and FUN! I've owned mine for over a year and I still marvel at the engineering every time I take it on a trip.

Got modding plans yet?? Widen that lean burn window!