Car Insurance doesn't lapse immediately because of a missed payment and you're usually still covered even when a missed payment for the car insurance has happened.
Before your car insurance actually lapses and is cancelled the car insurance company will send you a notice usually through the mail and let you know that you need to make payment or the car insurance will be lapsed and then cancelled.
The car insurance lapse can happen within 10 days or may not happen until 20 days after you miss the car insurance payment.
So make sure you make the car insurance payments on time or within 10 days to avoid your car insurance from lapsing because then you would not be covered in the event of an accident and you can get fined for not having car insurance.