I've been using 12,000 miles as a estimate of the number of miles people drive annually. Thats roughly what its been in the recent past but it tends to go up gradually over time. The Dept. of Transportation Federal Highway administration has data on the amount of miles people drive.
Here are the numbers :
These numbers were updated as of April 2011.
The average miles driven annually across the entire population is 13,476.
It is notable that the amount of miles drives varies significantly across age groups and between the genders. For all age groups women dirve a less than men and sometimes a lot less. Overall women drive around 38% less than men do.
Teens and seniors drive less than middle age adults. The amount people drive peaks in the 20 to 34 and 35-54 age groups which makes sense because thats the prime working years so you've got more miles driven commuting to work.
Of course the national averages don't really mean too much to individuals. Each of us drives a different amount given out own circumstances. There are undoubtedly some women out their in their 60's who drive 20,000 miles a year and men in their 30's who don't even clock 1,000 miles.