Well considering Jay Leno has been The Tonight Show host sincse 1992 - thats 11 years - at the declared salary of $17 million per year... (Half of Dave Lettermans $30 odd million ) that means he has pocketed about $170 million less taxes (and at $17 million a year, you will have very astute acountants and tax attorneys on your payroll).
With some money management and such, $17 mill a year is more than enough to feed a crazy gearhead habit.
Now - as to why he would not use his NBC money for 10 years is beyond me..