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Old 01-15-2013, 12:27 PM   #1 (permalink)
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Frogger - '00 Honda Insight Gas Only (unHybrid)
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Winter driving: Best way to keep those MPGs?

Hey gang,

Here in Idaho, we typically see winters that don't keep snow around long... usually stays between 20-40*F. This January, we've seen a lot of 0-25*F days. My home's heating bill is definitely proving the harsh times, but also, my last fillup was the 2nd lowest I have had with this car! 8-9MPG less than my average, I got ~35MPG (all city). All winter, I tried to drive it like I have been: Shifting at my estimated maximum BSFC recommneded 3.5K. I don't actually have a chart for my engine, on top of various modifications, but looking at other charts for similar engines, I made this my determined point (and tested various shift points with little/no difference) Regardless, Summer time weather had proven it to be fine, where I'm really seeing some suffering in this bitter chilled weather.

My intake is not pulling in warm air of any kind and my engine is not getting pre-warmed with any heater elements. I keep the car in a garage, but with the outside getting as cold as it's been, ~40*F seems to be the norm in my garage. I realize a few mods can easily make my car warmer and keep better mileage, but I wanted to make a thread on driving in conditions like winter offers. I bundle up and don't touch my heater at all on the way to work in the mornings to keep engine heat going as well as I can, plus, by the time I get to work, the engine barely hits 100*F anyways.

So after that grossly disappointing tank, I decided I need to experiment in these cold temps a bit. On my way to work, I decided to throw out my usual shift points and try going a bit lower. I shifted at 2K instead of 3.5K. Everything else I kept the same: coast to the stops, engine off completely instead of any idle (unless ~10-15 seconds or less of coasting/idle time), etc. Before, with the 3.5K shifts, I was seeing 35-40MPG at the end of my trip with my scangauge. With 2K shifts, I ended dead on 50.0MPG this morning. Outside temps I believe were 4-7*F and everything else remained roughly the same.

It's going to take more testing, but it looks like colder weather likes lower RPMs thus far.

So, what tips can you give to further increase in these cold times?

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