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Old 09-01-2021, 11:28 AM   #9 (permalink)
aerohead
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longer highway

Quote:
Originally Posted by CommodAnt View Post
Hi Everyone,

Over many years (and several different vehicles - automatic and manual, sedan and 4WD), I have consistently found that my fuel economy is better on longer highway trips when the car is loaded up to the max with weight. Conventional wisdom says that this should not be the case with lower weight resulting in better fuel economy.

My thoughts are that this is due to either 1. the weight lowering the car (so less air goes underneath, hence less air resistance), or 2. The extra weight means you can glide longer down inclines, with the engine operating more efficiently (harder) in pulling the vehicle up the hills.

Anyone else have any real world data or thoughts on what is going on?
1) the answer is hiding in plain view.
2) the vehicle's inefficiency is during transient loads.
3) the longer highway drives keep throttling to a minimum, and the gearing keeps the engine close to it's brake-specific-fuel-consumption optimum.
4) if you could drive continuously at 35-40-mph around town, never stopping until you arrived at your destination, you'd see your highest-possible mpg.
5) AeroStealth's 2014 F-150 will do 22-mpg @ 62-mph (100-km/h ).
6) Same truck @ a constant 35-mph = 32-mpg.
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