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Old 01-20-2019, 08:56 PM   #36 (permalink)
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Originally Posted by jamesqf View Post
And of course the one-way trips downhill from the top of Carson Pass would see me getting 150 mph (the highest the Insight's gauge will show) for 50-60 miles :-)
But what is it on the return trip?

Originally Posted by jamesqf View Post
*I do realize that my idea of "hills" may differ from the norm :-)
Michigan doesn't have a lot of crazy hills, but those mountain passes in WV are insane. Definitely steeper than in Tennessee and out west. Can't compare to Vermont though. Closest I've been to is NY, and that was only the west part, and I had my Civic then.

Originally Posted by Ecky View Post
I have to wonder if your mountains aren't smaller than ours.

When I was down in MA my fuel economy improved from ~58mpg to upper 80's. It was a little warmer but I expect most of that is from things being less mountainous. It's frequently necessary to be in 3rd gear WoT to maintain speed in my car on Vermont highways, forget about lean burn.
This was actually through the steep mountain passes in West Virginia. 3rd gear at 80%+ load getting 30-40 MPG was frequently necessary to climb the hills. On some hills I could maintain 45-55 MPG if I got enough momentum on the downgrade.

Through Michigan and elsewhere where there aren't any mountain passes I got 80+ MPG like you did in MA.

I also let my speed dip down to as low as 40 MPH on the inclines if there is no traffic. On the downhill my MPG is always above 100, and I sometimes reach incriminating speeds, which helps maintain momentum and get better MPG. Being able to bleed off 35 MPH from 75 to 40 allows me to use less throttle going uphill. I also downshift before the hill to keep the RPMs around 2000 (2000 RPM in 3rd gear is better MPG AND power than 1500 or so RPM in 4th gear going uphill, probably BSFC related voodoo ). That's probably the biggest reason why I was able to get the 73.7 MPG through the passes.

Most of the traffic on I-64 is truckers, who on mountain grades aren't going much faster than I am, so I don't mind going that slow near the top of the pass. If I tried to maintain 55 MPH going up the passes my fuel economy would definitely be lower, but if I did that, then I would have to use engine braking on the downhill to avoid reaching dangerous speeds, and DFCO's savings over neutral coasting doesn't make up for losing 5-15 MPG on the incline. 40 MPH uphill and 75 MPH downhill, if split evenly, is an average speed of 56.25 MPH, which is pretty much the same speed I averaged outside the mountains.
2013 Toyota Prius C (my car) 65 MPG
2015 Mazda 3 iTouring Hatchback w/ Tech Package (wife's car) 40 MPG
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