In the 04 tax codes there is a change that allows individuals to either deduct state income taxes or state sales taxes. For those that do not pay income tax the choice is easy. For others, you can figure which is more beneficial and take the higher deduction. Great thing is that you can use a general table to figure deductible amount by state and then add the sales tax for a vehicle to that. The following is a link to the IRS publication for more answers.
http://www.irs.gov/pub/irs-pdf/p600.pdf
Enjoy and just remember that if we move to a national sales tax (fair tax plan) you will never need to file taxes again.
Make April 15 just another day.
Jared