Chevrolet 2003 Impala Owner's Manual page 17

Your vehicle has a light
that comes on as a
reminder to buckle up. See
Safety Belt Reminder
Light on page 3-31.
In most states and in all Canadian provinces, the law
says to wear safety belts. Here's why: They
work.
You never know if you'll be in a crash. If you do have a
crash, you don't know if it will be a bad one.
A few crashes are mild, and some crashes can be so
serious that even buckled up, a person wouldn't survive.
But most crashes are in between. In many of them,
people who buckle up can survive and sometimes walk
away. Without belts they could have been badly hurt
or killed.
Why Safety Belts Work
When you ride in or on anything, you go as fast as
it goes.
After more than 30 years of safety belts in vehicles, the
facts are clear. In most crashes buckling up does
matter ... a lot!
Take the simplest vehicle. Suppose it's just a seat on
wheels.