Your personal auto insurance won't cover business vehicle use, so you need commercial auto insurance for any vehicle you use for work. Otherwise, you're putting your business at risk for liability claims from accidents during work-related trips.
When employees use personal vehicles for business purposes, like driving to client meetings, making deliveries or running errands, you need a different type of coverage. Hired and non-owned auto (HNOA) provides liability protection when employees drive their own cars for business or when you rent vehicles.