If you have an insurance policy to drive any vehicle would you still be insured to drive a car that is not insured by the owner?

The answer is "it depends." I know of no insurance companies that issue policies "to drive any vehicle" ... automobile insurance, at least in the USA, is based on the car being driven. In that case, the insurance is actually on the automobile, not on the driver. Therefore, an uninsured car would not be insured regardless of the driver. There may be exceptions, depending on the underwriter and the particular policy involved.