Quote:
Originally Posted by Phase
so its based on load? that would explaid why if i have a MILD tailwind ( nothing crazy) and i have my car on cruise controll, i can be going 80 miles per hour and my mpg will skyrocket to like 70-75 mpg! the mpg boosts big time. even better than going 55-60mph with no wind at all
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Theoretically, if the engine remained at a constant BSFC, and you drive in a tailwind, compared to 'calm,' you'd simply take your road speed and subtract the tailwind velocity to arrive at the 'apparent wind' that the IONIQ is experiencing.
Since the BSFC is 'constant' your mpg is going to just track the change in the aero portion of the road load.
Rolling resistance is unaffected.
Take the ratio of the cubes of your 'apparent' speed, divided by your speedometer speed, and multiply your original aero horsepower portion by that fraction to get your new aero load.
Add that back to the R-R horsepower ( which hasn't changed ), and you have the new road load in a tailwind.
Factor for your powertrain and accessories efficiency to get the new brake-horsepower being consumed.
Multiply that by your BSFC.
That gives you pounds fuel/hour at that speed.
Divide that by 6.138-pounds/gallon ( REGULAR E10 ) to get your gallons.
Divide your distance in an hour by the new gallons to spit out the new mpg.
