Why would you do that? You would never be reimbursed enough to offset, gas, wear & tear (mileage), depreciation, insurance, etc... Mileage reimbursement is almost always a losing proposition. Companies try to get away with something close to the tax reimbursement of 0.555/mile. Or a $500/month allowance. Try and rent or lease a vehicle for that - you can't. Take the company car and gas card and regular maintanance, etc... you will be better off. Less hassle too. However, if money is no object and you want to drive your own personal luxury car around all day - starting and stopping the engine, dings in parking lot, etc... then go for it!