Yes it is. Here is why! In California in order to drive rental vehicles you need a TCP License. You have to carry a minimum of a $750K  Commercial Liability Insurance. We have that. Ours is with Northland Insurance.   There are only a handful of legal Driving companies that are licensed & insured to drive Rental vehicles.

Most of the illegal Napa or Sonoma Designated Driver companies try to get you to let them sign on your insurance at the Rental Car agencies. If he/she gets in an accident god forbid, and kills someone with no commercial insurance you possibly could be on the hook. Ask yourself what are you saving by hiring that illegal driving company?

To Do List Checking Driving Companies For Legitimacy.

1. Ask the driving company if they have a TCP License from the CPUC of California. If they say no HANG UP!
2.  If you choose to use an unlicensed company please ask the driver to bring a copy of a current DMV report regarding his/her license. You want them to have a drivers license correct? Also notify your insurance carrier you intend to use a company that does not have a State Licensed TCP number to drive your rental car with no commercial insurance.  You have a duty to protect your insurance. If you do not believe that statement please ask your agent.
3. It is a requirement for anyone to have insurance to drive any vehicle even if your insurance follows you or your car.
4. Ask them if they have done drug testing and have there clearance to drive.
5. Would you let a non-licensed building contractor build your house? Yes it is the same!
6. LIST OF ILLEGAL DRIVING COMPANIES IN NAPA & SONOMA BELOW IN RED. NO TCP License and/or Insurance. We Drive. My Napa Valley Driver. Napa Private Driver. 

Here are the links below for the CPUC to prove you need a TCP License to drive rental cars.

Licensing Requirements for Passenger, Household Goods Carriers

CHARTER-PARTY CARRIERS charter their vehicles for the exclusive use of an individual or group. Examples are a group charter of a bus to go to a sporting event and the charter of a limousine for a wedding. Also falling under the charter-party category are some specialized types of passenger carrier services:

• Round-trip sightseeing service
• Transportation incidental to another business
• Transportation under contract to a business, government agency, or private school
• Transportation of agricultural workers to and from farms

Information and resources for charter-party carrier licensing requirements

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Hired Drivers (PUC §5360) CLICK THE LINK BELOW AND GO TO THE BOTTOM OF THE PAGE. 

Information and resources for hired drivers using rented vehicles – licensing requirements

BOOK NOW A LEGAL DRIVING SERVICE