How is the money divided for the NASCAR drivers?

I see that some drivers who finish at the back of the pack sometimes make more $$ than those who finish better. Is it experience? Years in NASCAR? Sponsors? How many cars they passed or where they came from in the line up to win…what are all the factors in dipersing the cash??
diSpersing the cash I meant
Thanks! You all get a thumbs up from me!!

it has to do with not only how the race "purse money" is divvied up, but also how "big a draw" the driver is – is he the current champion, a past champion, won multiple championships, won many races recently, etc. also, there are contingency prizes, pole award winnings, and sponsor-related prizes, etc. and there are many others – like leading a certain lap (usually at half-way), leading the most laps, winning a race as the cup points leader, etc.

this confused me for quite some time. there are a few good articles about this on nascar.com, and some that are near indecipherable. here’s a few articles that deal with the topic:

http://www.nascar.com/news/features/race.winnings/index.html

http://www.nascar.com/news/features/special.awards/index.html

http://www.nascar.com/2005/news/features/last_lap/12/13/last_lap_12-13/index.html

http://www.nascar.com/2004/news/business/07/21/follow_money/