Efficiency/Economy comparisons to Honda Fit

[cinder]

Is the '09 FIT an auto or manual ?

[cinder]

Canoehead , we bounce back and forth on cars . A car salesperson worst nightmare .

[Minihaha]

OK here ...

OK it works, there's a lot of data there, but just notice the mpg vs mid readings.! Also the 37.77 lifetime mpg.

Yeah, wth - the MID appears to be about worthless, and wildly optimistic. Essentially most FIT owners would likely be clueless about the true fuel efficiency of their cars, or am I missing something?

[Canoehead]

Yeah, wth - the MID appears to be about worthless, and wildly optimistic. Essentially most FIT owners would likely be clueless about the true fuel efficiency of their cars, or am I missing something?

I just skimmed the data. At first, it seemed the MID was reasonably consistent at 12% over-estimating. Then I saw swings where it went from right on to 40% over. If the error was consistent and repeatable it could still be useful, but I see you are correct that it isn't much good at all.

Does anyone have any idea why it is so wrong?

Are there particular circumstances (extreme cold? short trips? idling? highway driving? fuel additives?) that exacerbate the problem?

[DonHoot]

Is the '09 FIT an auto or manual ?

Automatic. I would hate to accuse Honda of overstating the mileage, but maybe they know most people never actually check the mileage. I just don't know how accurately the car computer can measure fuel flow? (Anybody know how accurately gasoline flow can be measured?).

[MetroMPG]

They typically don't measure fuel consumption directly. They measure air consumption and extrapolate fuel consumption based on a/f ratio.

I would hate to accuse Honda of overstating the mileage

That practice is getting harder and harder to do. People definitely track and share their mileage. Car companies now get sued (in the U.S.) when the ratings are too far off.

Also, the EPA has stepped up auditing of manufacturers to ensure the submitted numbers are repeatable in independent testing. Mercedes Benz was just caught overstating one of its cars. Article: EPA to Fortify Certification Oversight in Wake of Mileage Controversies

[Canoehead]

They typically don't measure fuel consumption directly. They measure air consumption and extrapolate fuel consumption based on a/f ratio.

That's how it is done for athletes to (VO2Max test). So knowing that, what makes the MID so wrong? Is it an issue of air pressure/density/temperature? Does some of the fuel remain uncombusted and go through the system without oxidizing (air used, but no fuel burned)? Is the scan-gauge any better than the on-board systems?

[cinder]

Here's the original gas mileage estimates posted in window of each FIT when new . The top is the '11 and below the '13 . Both are base with a 5 speed auto and exceed the fuel economy estimates .

[MetroMPG]

So knowing that, what makes the MID so wrong? Is it an issue of air pressure/density/temperature? Does some of the fuel remain uncombusted and go through the system without oxidizing (air used, but no fuel burned)?

Good question. To start, most factory displays are significantly optimistic -- 10% isn't unusual. (FYI, the Mirage's wasn't too far off in my experience - under 5% optimistic over the 3 fills I tracked.)

Maybe by extrapolating from stoich, they don't properly account for additional fuel used during warm-up mode (running rich below a certain coolant temp threshold). Or in open loop mode (WOT).

Is the scan-gauge any better than the on-board systems?

Yes, because it's adjustable. You can calibrate a ScanGauge to a specific vehicle by ajusting offsets for both fuel use and distance covered.

[MetroMPG]

PS: Green Car Reports just did a "gas mileage test" of the 2015 Fit CVT and got 39 mpg US in a trip that was ~2/3 highway. Uncharacteristically, they used "Eco mode" some of the time (which I don't believe they normally do).

The writer is not a fan of eco-driving, despite the eco-focus of the blog:

http://www.greencarreports.com/news/...compact-or-not