Personal Liability when visiting the States

Hope someone can help here from past experience--

Whenever we've visited the states we've rented a car and as such had comprehensive insurance.  This time when we go, I'm going to just use my dad's car.  Now, he's obv got collision damage waiver and all that jazz, but since I'm not on his insurance policy, there's nothing to cover my liabilities if I do any damage.

My travel insurance (AIG) covers me up to £2m but that doesn't include while driving (even though I've got an american licence).

Does anyone know how I can cover myself for liabilities while I'm in the states?  I've tried my normal insurance (norwich union) but they say they won't cover me in the states.

Any suggestions?

THanks

Have your dad check with his insurance provider. From what I understand some companies will let you add someone temporarily to your insurance that you want to give permission to drive your car... so for a few days or weeks, however long you will be there.

My take.
As long as your Dad has given you permission to drive the car then you are covered on his policy.