Our Smartcar is insured through Progressive with owned-vehicle delivery liability insurance. We also carry a separate non-owned delivery insurance since all our current drivers use their personal vehicles to deliver unless they have car trouble.
The insurance rate on the owned policy is basically set according to the “worst” driver insured on the policy. I have 20-some people on the policy and the premium only changes if I add someone that is higher risk than normal (or remove that person).
On a side note, I really like working with Progressive. Maybe it’s because of the commercial policy, but they are always super friendly on the phone.