Yes, a grace period of 15 to 30 days is there for car insurance renewal. It depends on the terms and conditions of the policy of your insurance company. You can also renew your policy after the grace period but you will have to pay an extra amount.
There is no grace period after insurance expires under law. While you can renew the car insurance after the grace period, you may have to pay the penalty or late fee apart from losing benefits such as NCB.