Speed and gas mileage

Trade one for another!

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Trading pounds of manure, urine and rotting flesh for grams of hydrocarbons and nitrogen oxides.

People were immigrating to NYC back then because they thought the streets “were paved with gold”. Then they got here and found the streets were paved with sh*t.

Air resistance goes up as the cube of the speed, so fuel consumption per mile goes up as the square (this is a big factor with airplanes). With cars there are other factors such as rolling resistance and the efficiency of engine and drivetrain as a function of speed that might affect the overall percentage (a car probably gets better mileage just above the speed of a shift than just below it), but the wind resistance relationship still is there.

Yes, I’ve always felt I get my best mileage just about auto shift “sound.” I get 33 mpg in 2013 Honda Fit base.

There are a lot of different things going on in my opinion. My 2015 Cherokee has the 3.2L V6 and a 9-speed trans (for the record, I’ve had it up to 80 mph on a relatively empty straight and flat stretch of I-5 between Sacramento and Bakersfield and it never did go into 9th gear). According to the mileage computer I actually get my best mileage at about 40-45 mph (about 45 mpg). So I’d guess it’s a combination of the overall gearing, aerodynamics of the vehicle and the power (I’m guessing a torquier engine might upshift at a lower rpm, providing better mileage, but that’s an impression, not a researched fact).

When you let off the throttle at 80 it should have gone in to 9th gear. That’s what those high gears are for.

At this point in my life I’ve got more money than time so I’ll drive 70 or so regardless of wind shear.


Life is full of “should haves”, “would haves”, and “could haves”. :frowning:

It didn’t.

Like I said, on a two lane, I had one opportunity to go around two cars. I hit the gas hard and went into passing gear. When I looked down I was going 90. I don’t know what my mpg was but passing gear is a lower gear and quite sure I was no longer in overdrive. Surprised the car went that fast that quick. We were allowed to go 65 in a 55 for passing so I was a little above that. A while back when gas was $2.