re: Anyone in sales and have a car allowance/gas card?

You need to do both. You need to pay taxes or take a deduction based on if your reimbursement (and gas money) is more or less than the mileage would come out to be. Instead of mileage you can do actual expenses including depreciation. I think....

Just reread the OP. IF you are paying taxes on the car allowance, you absolutely need to turn in your mileage and any other expenses you incur while providing a vehicle to your employer. Most vehicle allowances are not taxed though because they are seen as a reimbursement.