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"SWEET SPOT" FOR FUEL ECONOMY HIGHWAY DRIVING

Created September 16, 2008, at 2:49 am by thompson

BACKGROUND: I own a 2006 HCH II. I recently took a business trip from San Antonio, TX to Kansas City, MO. Total miles on trip was 2,250, with 1,700 miles via I-35. Balance of miles was "in and around" miles.

DISCUSSION: The essence of my question/comment is what is the "sweet spot" for fuel economy on such a trip. The terrain between here and Kansas City is essentially flat to gently rolling hills on I-35 (with exception in southern/eastern Kansas for the Flint Hills). I kept my Cruise Control in the on position most of the time set at 60 MPH. I averaged 54.2 MPG for the entire trip. Trip was in July 2008. Daytime temperature highs were over 90 degrees. Wind on I-35 was essentially neutral. I felt a speed less than 60 MPH made me an "accident waiting to happen". How could I have done better, without getting into the "hyper-mile" type techniques?

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MSantos
Senior Member

3 years ago

Yes, you *could* have done better but I would not call that the result of any hypermiling technique. However, hypermilers are adept at finding Easter Eggs in many of today's hybrids and the HCH-II has a few one of which is a Super Highway Mode.

The HCH-2 can achieve exceptional mileage provided that you get it into the SAHM mode. In this mode you can easily get 70-90 MPG while traveling at speeds of 55-62 MPH. By the way, cruise control is a NO-NO.

You can see it here:
http://www.cleanmpg.com/forums/showthread.php?t=14295

Cheers;

MSantos

Anonymous

3 years ago

Santos

I was wondering at what speed you can achieve 70mpg. And how long can you hold it.

Thanks

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MSantos
Senior Member

3 years ago

70MPG?

With the car on SAHM mode that's just the start and it can be held for as long as you allow it.

When I do a highway trip (solo) I can easily attain 80-90 MPG running at 55-62 MPH. Wit a loaded car I will score a 69-75 MPG at the same speeds.

Cheers;

MSantos

Anonymous

3 years ago

My trips are mostly on hiway 25 miles each way.Is a scangauge neccesary
to get the high mpg

Thanks again

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MSantos
Senior Member

3 years ago

I've had people tell me they manage to use the SAHM mode without the need for a scangauge... but I doubt they can hold the mode steady solely by the seat of their pants. I know I can't since the optimal IGN and LOD ranges are very narrow and that makes the Scangauge a must have in my book.

Cheers;

MSantos

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hansonclan
Junior Member

3 years ago

Scanguage not necessary, although I don't doubt it would help. It's quite obvious when it's in the "Super Atkinson Highway Mode" when the iFCD is in the 75-100 mpg range. It's easy to keep it there, as long as the grade of the road and winds cooperate. I don't imagine a Scanguage will do much to flatten out the hills or reduce the headwinds either.

Tire pressure seems to be a big player too. I found to my dismay that my stock Dunlops don't seem to want to hold 44 psi. I have to top them off every week with 2-3 psi. I discovered that by experiencing difficulty in staying in SAHM during my normal commute. Top off the tires - back to normal.

My car was improving steadily as it broke in, and as I learned techniques from this and other forums, until now I seem to have reached a plateau of 64mpg now for my commute at around 2500 miles on the odometer. I'm quite sure that if I could do a long highway trip I would see 70+.

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manojjonam10
Senior Member

3 years ago

I wonder how you change your speed in the terrain and the percentage of brakes you apply for an average trip.

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