Bottom line is the vehicle is not yours. I drive with that in mind and am fully aware that if I abuse that, my boss has the right to discipline me. If it makes to his boss, I might be looking for a job somewhere else. Use some common sense and good judgement and you have nothing to worry about. If you don't know what the policy about vehicle use is, then ask, because I promise you the company you work for has a written policy somewhere about it.