The estimate is a crap figure
Lets say you commute, the national average in cities is about 25 minutes.. but lets make it an even thirty to make the math easier.
30 minute commute each way to work... 1 hour per day 5 days a week = 5 hours
Lets say you go to the gym, and that adds 15 minutes each way... another 1/2 hour and you do that 3 days a week.. you’re pretty dedicated... so 1.5 hours per week.
Lets say you do typical shopping or errands during the week.. maybe 30 minutes per trip 2-3 trips a week... another 1 to 1.5 hours per week
And lets say on weekends you are running around like crazy and like to hit the open road and go places... another say 4 hours per day for 2 days.. 8 hours
So all that tallied up adds up to 15.5 hours on the top side. and I really don’t think folks spend 4 hours a day on the weekends in their car.. but giving that as an outrageous example. you still don’t get to 21 hours per week.
10-15 would be my guess for the typical person in their car.
I know a lot of people who spend more than that in their car.
In my area a 45 minute to 1 hour commute is average. Going anywhere to shop is a 30 minute to 1 drive each way.
I’d say the 15-20 hour range for total car time is realistic.
You are completely forgetting those of us with 4 kids who have track meets, karate lessons, ballet, music lessons, Little League practice 3x week + games 2x week, Boy Scouts, cub scouts, weekend trips away. . .
Moms are constantly in their cars.
And for the past 13 years my commute was 2 hours one way (live 45 miles East of San Francisco); last year I moved just 14 miles northwest and my commute is now under an hour. Freeway traffic makes a big difference. . .(I take a different freeway now, plus BART).