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Old 09-25-2018, 09:29 PM   #106 (permalink)
Ecky
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Join Date: Dec 2011
Location: New Zealand
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ND Miata - '15 Mazda MX-5 Special Package
90 day: 40.51 mpg (US)
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Quote:
Originally Posted by mpg_numbers_guy View Post
So unless the battery is actually dead it's better to leave it hooked up?
I'd say that's usually the case. When it gets very near the absolute end, it can start causing the car to regenerate a lot more to keep the battery up, which won't hold a charge anymore, but often it still saves fuel at this point just from auto-stop.


Quote:
Originally Posted by mpg_numbers_guy View Post
Oh. My. Word. That is just crazy amazing. Thank you so much for sharing!!

Out of curiosity, when climbing a slight grade, is it better to "floor" it in 5th gear or downshift into 4th and maintain lean burn?
You'll find contention about this. I don't think there are any BSFC charts for lean burn. There are some who believe BSFC is better, period, when in lean burn, and will do things like run 3rd gear in learn burn rather than 5th gear at times. There are others who suspect lean burn just improves BSFC at part throttle, but that ultimately it's better to run the engine at lower RPM when you can - after all, vacuum is the same, but friction is lower and all of the accessories are spinning lower so you have fewer parasitic losses.

I personally know of one person who averages 130+ mpg without lean burn at all, FWIW, but he's crazy. My testing has shown that it was worth at least 10mpg on my old commute, but I lean toward the 2nd camp.


Quote:
Originally Posted by mpg_numbers_guy View Post
I return home for winter break the 2nd week of December. Then I drive my Civic doing pizza delivery...in winter weather...where despite mods breaking over 40 MPG will be a challenge...until 2nd week of January when I sell it and return to college. Then when I return home for spring break I'll be on the hunt for an Insight. Oh why does it have to be this long of a wait!!
Good luck and happy hunting! It's important to remember that even as reliable as these are, they're still nearing 20 years old. There may be a lot of small "tune-up" items you'll want to do to maximize economy, even on a very clean one. Things like greasing the brake calipers (reduces brake drag), cleaning the EGR passages, coolant, fresh transmission fluid, the sort of stuff that really should be done on any car but is neglected on most.
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