Yes, you can require employees to use a personal vehicle for work, and for many employers, this may seem safer than providing company cars. The use of privately-owned automobiles for approved work is permissible provided it is done during the course of the employee's scheduled hours of work.It is lawful for your employer to make you use your own vehicle to drive to various locations for your job. California Mileage Reimbursement Law requires employers to reimburse employees for all vehicle expenses incurred on the job. You are entitled to be reimbursed all expenses you incur to do your job. Texas doesn't have any state laws governing car allowances. Does your organization employ anyone who travels for work using a personal vehicle? So the days you are in TX are subject to TX laws (no income tax), but the days you are working in CA are subject to CA income tax. Your employment contract should have a separate page for drivers.