According to this Bloomberg article, charging your phone in the car eats up your mileage.
The math is that it costs you 0.03 miles per gallon to charge your phone in the car.
Assume $2 a gallon.
If you drive a used Jeep that gets 16 mpg and the tank holds 18 gallons and you drive it till empty every week, that’s 288 miles every week driven.
But the 18 gallons a week x 52 weeks in a year = 936 gallons you use in the year, all else constant.
Of the 936 gallons, if what the article is saying is approximately the thing that’s going on, and I only skimmed through it, that’s:
0.03 miles/gallon x 936 gallons = 28 miles a year wasted.
That’s for the old Jeep if the driver charges their phone everyday in the car.
That’s approximately 2 gallons of gas wasted, or $4.
Spread across the millions of drivers in America alone, that’s millions of gallons of oil and dollars wasted to charge a phone in the car.
Some More Math:
They point out that it’s better to charge your phone at home because it costs 0.06 cents to charge your phone for an hour at home versus 2 cents an hour with gasoline at $2 a gallon.
If you charge your phone for an hour in the car everyday, for a 30 minute commute to work and 30 minute commute home, that’s 2 cents x 365 days, assuming you work every day of the week.
2 cents x 365 days = $7.3 a year for charging your phone in the car.
0.06 cents x 365 days (assuming you charge your phone for an hour each day at home) = $2.19
That’s roughly a $5 difference.
Spread across the rest of North America alone, that’s millions of dollars that could be saved if people just charge their phones at home!