I’ve been doing a good amount of business travel lately. My employer reimburses mileage and provides a per diem. However, both those amounts are below the standard IRS rates. For instance, the IRS mileage deduction is {content}.485 per mile, while my company reimburses {content}.405 cents per mile. The IRS per diem for the region I travel to is / day while my company pays / day.
When I file my 2007 taxes, can I claim the difference between the allowable and actual reimbursements and an unreimbursed business expense?
I travelled 2,000 miles for business, so was reimbursed 0. At the IRS mileage rate, that would have been 0. Can I claim the 0 as an unreimbursed business expense? Is the scenario different for mileage and the per diem?

I’d prefer answers from folks who have actually faced the situation (or tax specialists) rather than speculation. Many thanks!

I made 95000 last year, I am single, no dependents, no house, I went to HR block last year and I got back a very small amount for my return. I use my personal vehicle for business about 70% of the time. I have logs of this information. I have a 401K and pay into bi monthly. I get paid a per diem while at work, but it seems to be below the standard for where I work. Any help would be greatly appreciated. Also, will I be able to get more money back from last year since HR Block didn’t advise me of any deductions such as mileage and per diem?