I drive my car for business, my emplyoyer pays allowance and gas. do I get to deduct any miles? Im a sales rep and have a large territory to cover. never the same.

allowance is 600 before taxes, car payment and insurance is 550. I'm confused if I can write off miles and also commuting miles are confusing. I don't have an office, I travel to different offices as a sales rep in a large territory. It's different every week.