Hi, and welcome to JA!
The average American spends 101 minutes a day driving (according to the 2007 Harvard Health Watch, see ref: http://www.revolutionhealth.com/blogs/drscherger/men-moderate-exercis-3815)
Using an average lifespan of 77.2 years (http://www.aarp.org/bulletin/yourhealth/a2004-07-07-methuselah.html), and assuming that the above average includes people of every age, we can multiply out:
101 minutes / day * 365.25 days / year * 77.2 years = XXXXXXX.3 minutes driving
= 47465.455 hours
= 1977.72 days
= 5.42 years
Given an average lifespan, the average person is driving for 7% of their life.
I hope this helps. Let me know if you have any questions. Don't forget that the only way I get credit for helping you is if you press "Accept". Thanks!
Scott
MIT Graduate
MIT Graduate, United States Traveler, Information Finder