Can someone borrow off of their physical damage insurance?
no== Answer ==I do not know of a scenario where this is remotely possible. Perhaps more details..
If you borrow a friend's car with permission are you covered under their auto insurance?
Generally barring any exclusion in the policy.
What if someone else drove your car caused damage only to your car can you ask him to claim the damage on his insurance?
Answer The car's insurance would kick in first because YOU gave them permission. Their insurance would pay for whatever is left over.
Will an auto insurance company repair a car that has had an electrical fire even if there is no physical damage to the body of the car?
Answer yes. it is a covered loss Payable under comprehensive or "other than collison"
If a vehicle owned by someone else is not insured and you borrow it will your personal insurance take over and cover you in case of an accident?
Answer If you are using it because your vehicle is in the shop for repairs, generally, yes. However, I would call my agent or the claims department to verify.