As long as you have permission, you are not a regular user and you are not specifically excluded, you can drive your friends vehicle. This generally holds true in all US states as well.

Hello

If the same as U.K
All they have to do is have you added to their policy as a named driver.
Normally an £30 Admin fee only but get your friend to get a price first and they will need all your details.

Andy C

Yes, as long as you have his permission. If you drive it regularly–say, once a week or more, you should be listed as a driver. Be sure you know where the insurance ID card is kept in the car.