Quote:
Originally Posted by tryg26
So I know that highway mpg is mostly affect by wind resistance but what are the main factors that change city mpg? Weight, Engine Efficiency??
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The difference —
in what matters —is the amount of time at steady state per engine hour.
The simple test is to find “best” fuel economy highway at under 60-mph while on cruise control. A 100-mile loop back to the same fuel station pump. Re-fill to first auto shutoff.
While on town miles, “never idle and never stop” is the mantra.
Plan all trips. Eliminate cold starts. Combine all errands.
I did this several years back and brought my one-ton pickup to 22-mpg city for over 1,000-miles. An improvement of 20%. 25-highway was an established norm.
The point to the exercise is to know what’s possible. With no other changes (no stunt driving). A variation of only 13% between highway and city is pretty low.
The guy who is SERIOUS about fuel economy in a one ton Dodge diesel got into the mid 40-mpg range using all available driving techniques (Diesel Dave).
The only competition is against one’s self. Keep records of every fillup (Fuelly) and get the trend started the right direction. Fewer trips over fewer miles to accomplish THE EXACT SAME ENDS is how it works.
Thanks for the link, CapriRacer. It’s the cold engine + stop/start driving that really distinguishes the difference between town & country for a given passenger vehicle.
On-highway ONLY (such as long distance trucks) are where aero benefits really pay (modifications to existing).
Engine time on the highway versus engine time in metro traffic is HEAVILY skewed to the latter for nearly everyone.
FE is a collection of changes. But the biggest is
Operator Usage. And one CANNOT separate out aero or other changes unless baseline records and repeatable testing procedure is established. Until one understands the relationship between AVERAGE MPH and AVERAGE MPG most efforts won’t bear fruit.
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